Effects of Electrical Stimulation on Molecular Forms of Butyrylcholinesterase in Denervated Fast and Slow Latissimus Dorsi Muscles of Newly Hatched Chicken

The effects of denervation and direct electrical stimulation upon the activity and the molecular form distribution of butyrylcholinesterase (BuChE) were studied in fast-twitch posterior latissimus dorsi (PLD) and in slow-tonic anterior latissimus dorsi (ALD) muscles of newly hatched chicken. In PLD muscle, denervation performed at day 2 substantially reduced the rate of rapid decrease of BuChE specific activity which takes place during normal development, whereas in the case of ALD muscle little change was observed. Moreover, the asymmetric forms which were dramatically reduced in denervated PLD muscle were virtually absent in denervated ALD muscle at day 14. Denervated PLD and ALD muscles were stimulated from day 4 to day 14 of age. Two patterns of stimulation were applied, either 5-Hz frequency (slow rhythm) or 40-Hz frequency (fast rhythm). Both patterns of stimulation provided the same number of impulses per day (about 61,000). In PLD muscle, electrical stimulation almost totally prevented the postdenervation loss in asymmetric forms and led to a decrease in BuChE specific activity. In ALD muscle, electrical stimulation partially prevented the asymmetric form loss which occurs after denervation. This study emphasizes the role of evoked muscle activity in the regulation of BuChE asymmetric forms in the fast PLD muscle and the differential response of denervated slow and fast muscles to electrical stimulation.     

Expression of the Ganglioside GD3 in Human Meningiomas Is Associated with Monosomy of Chromosome 22

The ganglioside composition of 59 meningiomas has been compared with a molecular genetic analysis of chromosome 22 in the same specimens. Major gangliosides were GM3 (II3NeuAc-LacCer) and/or GD3 [II3(NeuAc)2-LacCer]. In specimens with no or partial deletions of chromosome 22, the GM3 ganglioside predominated, and the mean value for GM3, 61% of total sialic acid, was around four times higher than that for GD3. A loss of chromosome 22, found in 56% of the specimens, was shown to be associated with an increase in the proportion of ganglioside GD3, with the ratio between mean values of GM3 and GD3 being approximately 1:1. Logistic regression revealed that the probability of predicting monosomy of chromosome 22 by the GD3 proportion was 66%.     

Mitochondrial DNA evolution in theDrosophila nasuta subgroup of species

Summary TheDrosophila nasuta group consists of about 12 closely related species distributed throughout the Indo-Pacific region. They are of great interest because of their evolutionary idiosyncrasies including little morphological differentiation, the ability to intercross in the laboratory often producing fertile offspring, and substantial chromosomal evolution. Studies of metric traits, reproductive isolation, and chromosomal and enzyme polymorphisms have failed to resolve the phylogeny of the species. We report the results of a survey of the mitochondrial DNA (mtDNA) restriction patterns of the species. The phylogeny obtained is consistent with other available information and suggests thatD. albomicans may represent the ancestral lineage of the group. The amount of polymorphism in local populations (=1.0% per site) is within the typical range observed in other animals, includingDrosophila. The degree of differentiation between species is, however, low: the origin of the group is tentatively dated about 6–8 million years ago. This study confirms the usefulness of mtDNA restriction patterns for ascertaining the phylogeny of closely related species.     

Rates of synonymous substitution in plant nuclear genes

Summary The rate of synonymous nucleotide substitution in nuclear genes of higher plants has been estimated. The rate varies among genes by a factor of up to two, in a manner that is not immediately explicable in terms of base composition or codon usage bias. The average rate, in both monocots and dicots, is about four times higher than that in chloroplast genes. This leads to an estimated absolute silent substitution rate of 6 × 10^–9 substitutions per site per year that falls within the range of average rates (2–8 × 10^–9) seen in different mammalian nuclear genomes.     

A meristic, morphometric and biochemical investigation of Atlantic menhaden, Brevoortia tyrannus (Latrobe)

Juvenile Atlantic menhaden, Brevoortia tyrannus , were collected from estuarine waters of the Atlantic coast of the United States. Those collected north of latitude 40°N had lower numbers of total and trunk vertebrae, ventral scutes and interhaemal spines, and shallower heads, smaller eyes, shorter predorsal lengths, and lower frequencies of the fastest allele observed at the transferrin locus than those collected south of Long Island. Although the evidence is still inconclusive, the potential for at least two subpopulations still exists: one which spawns in the spring and early summer and is responsible for the primary recruitment in the northern North Atlantic area, and one which spawns in the autumn and winter and contributes the majority of recruitment in the middle and southern North Atlantic areas of the United States.     

Macromolecular adducts of ethylene oxide: a literature review and a time-course study on the formation of 7-(2-hydroxyethyl) guanine following exposures of rats by inhalation

The results of efforts to identify and quantify macromolecular adducts of ethylene oxide (ETO), to determine the source and significance of background levels of these adducts, and to generate molecular dosimetry data on these adducts are reviewed. A time-course study was conducted to investigate the formation and persistence of 7-(2-hydroxyethyl)guanine (7-HEG; Fig. 1) in various tissues of rats exposed to ETO by inhalation, providing information necessary for designing investigations on the molecular dosimetry of adducts of ETO. Male F344 rats were exposed 6 h/day for up to 4 weeks (5 days/wk) to 300 ppm ETO by inhalation. Another set of rats was exposed for 4 weeks to 300 ppm ETO, and then killed 1–10 days after cessation of exposures. DNA samples from control and treated rats were analyzed for 7-HEG using neutral thermal hydrolysis, HPLC separation, and fluorescence detection. The adduct was detectable in all tissues of treated rats following 1 day of ETO exposure and increased approximately linearly for 3–5 days before the rate of increase began to level off. Concentrations of 7-HEG were greatest in brain, but the extent of formation was similar in all tissues studied. The adduct disappeared slowly from DNA, with an apparent half-life approx. 7 days. The shape of the formation curve and the in vivo half-life indicate that 7-HEG will approach steady-state concentrations in rat DNA by 28 days of ETO exposure. The similarity in 7-HEG formation in target and nontarget tissues indicates that the tissue specificity for tumor induction is due to factors in addition to DNA-adduct formation.     

Evolutionary analysis of Pinus densata (Masters), a putative Tertiary hybrid.

Summary Restriction fragment analysis and heterologous hybridization of chloroplast (cp) DNA was used to develop species-specific markers for P. tabulaeformis, P. yunnanensis and P. massoniana. Fragment patterns created by the BclI and DraI restriction enzymes and hybridization patterns to the psbC and psbD probes were distinctive among the three species. No intraspecific variation was detected with respect to any of the cpDNA markers developed in this study. The cpDNA markers obtained were subsequently used to examine the parentage of P. densata, a putative Tertiary hybrid between P. tabulaeformis and P. yunnanensis. The analysis demonstrated for the first time that P. densata populations accommodate chloroplast genomes of P. tabulaeformis and P. yunnanensis, which strongly supports earlier suggestions of the hybrid origin of this species. It appears that P. densata represents a stabilized natural hybrid that has become adapted to high mountain environments where neither of the parental species can normally grow.     

Discrimination between closely related Triticeae species using genomic DNA as a probe

Summary Labelled total genomic DNA was used as a probe in combination with blocking DNA to discriminate between taxonomically closely related species in the genera Hordeum and Secale. Discrimination was possible both by Southern hybridization to size-fractionated restriction enzyme digests of genomic DNA and by in situ hybridization to chromosome preparations. To distinguish between two species (e.g. H. vulgare and H. bulbosum), genomic DNA from one species was used as the labelled probe, while unlabelled DNA from the other species was applied at a much higher concentration as a block. The blocking DNA presumably hybridized to sequences in common between the block and the labelled probe, and between the block and DNA sequences on the membrane or chromosomes in situ. If so, mainly species-specific sequences would remain as sites for probe hybridization. These species-specific sequences are dispersed and represent a substantial proportion of the genome (unlike many cloned, species-specific sequences). Consequently, rapid nonradioactive methods detected probe hybridization sites satisfactorily. The method was able to confirm the parentage of hybrid plants. It has potentially wide application in plant breeding for the detection of alien DNA transfer, and it can be easily adapted to many species.     

Brassica taxonomy based on nuclear restriction fragment length polymorphisms (RFLPs)

Summary RFLPs were used to study genome evolution and phylogeny in Brassica and related genera. Thirtyeight accessions, including 10 accessions of B. rapa (syn. campestris), 9 cultivated types of B. oleracea, 13 nine-chromosome wild brassicas related to B. oleracea, and 6 other species in Brassica and allied genera, were examined with more then 30 random genomic DNA probes, which identified RFLPs mapping to nine different linkage groups of the B. rapa genome. Based on the RFLP data, phylogenetic trees were constructed using the PAUP microcomputer program. Within B. rapa, accessions of pak choi, narinosa, and Chinese cabbage from East Asia constituted a group distinct from turnip and wild European populations, consistent with the hypothesis that B. rapa had two centers of domestication. A wild B. rapa accession from India was positioned in the tree between European types and East Asian types, suggesting an evolutionary pathway from Europe to India, then to South China. Cultivated B. oleracea morphotypes showed monophyletic origin with wild B. oleracea or B. alboglabra as possible ancestors. Various kales constitute a highly diverse group, and represent the primitive morphotypes of cultivated B. oleracea from which cabbage, broccoli, cauliflower, etc. probably have evolved. Cauliflower was found to be closely related to broccoli, whereas cabbage was closely related to leafy kales. A great diversity existed among the 13 collections of nine-chromosome wild brassicas related to B. oleracea, representing various taxonomic states from subspecies to species. Results from these studies suggested that two basic evolutionary pathways exist for the diploid species examined. One pathway gave rise to B. fruticulosa, B. nigra, and Sinapis arvensis, with B. adpressa or a close relative as the initial ancestor. Another pathway gave rise to B. oleracea and B. rapa, with Diplotaxis erucoides or a close relative as the initial ancestor. Raphanus sativus and Eruca sativus represented intermediate types between the two lineages, and might have been derived from introgression or hybridization between species belonging to different lineages. Molecular evidence for an ascending order of chromosome numbers in the evolution of Brassica and allied genera was obtained on the basis of RFLP data and phylogenetic analysis.     

Determination of trace elements in aerosol samples by Instrumental Neutron Activation Analysis

Two nuclear techniques, Energy-Dispersive X-Ray Fluorescence Analysis (EDXRF) and Instrumental Neutron Activation Analysis (INAA), were used to analyze aerosol samples collected in the city of São Paulo, Brazil. Na, Cl, Mn, V, Al, Sm, Mo, W, La, As, Br, Sb, K, Ba, Se, Th, Cr, Rb, Ca, Fe, Ce, and Sc were determined by INAA, and Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, As, Se, Br, Rb, Sr, Hg, and Pb were determined by EDXRF. A preliminary identification of the main source of the atmospheric aerosol was performed based on enrichment factor and correlation coefficient calculations.