Allozyme variability and phylogenetic relationships in the cultivated potato (Solanum tuberosum) and related species

Gene frequencies at 13 isozyme loci were determined in three South American taxa of cultivated potatoes [the diploid group (gp.) Stenotomum, the diploid subgroups (subgp.) Goniocalyx, and the tetraploid gp. Andigena ofS. tuberosum], in the diploid weed speciesS. sparsipilum, and in most of the main cultivars now raised in the Northern Hemisphere (the tetraploid gp. Tuberosum ofS. tuberosum). High levels of genetic variability (mean number of alleles per locus, percentage of polymorphic loci, and mean heterozygosity) were detected, being higher in tetraploid potatoes. An equilibrium among the evolutionary factors which increase genetic variability and artificial selection for maximum yield would explain the high uniformity of heterozygosity values we observed in both Andigena (0.36 ± 0.02) and Tuberosum (0.38 ± 0.01) cultivars.—The low value of genetic distance (D = 0.044) between Stenotomum and Goniocalyx does not support the status of species forS. goniocalyx.—In most isozyme loci, the electromorphs of gp. Andigena were a combination of those found in both gp. Stenotomum andS. sparsipilum, suggesting an amphidiploid origin of gp. Andigena from that two diploid taxa. The presence in Andigena of unique electromorphs, which were lacking in both gp. Stenotomum andS. sparsipilum, suggests that other diploid species could be also implied in the origin of tetraploid Andean potatoes. Furthermore, since Andigena were more related to Stenotomum (D = 0.052) than toS. sparsipilum (D = 0.241), the autopolyploidization of Stenotomum individuals and the subsequent hybridization with gp. Andigena may also have occurred. Thus, our study suggests a multiple origin (amphidiploidy, autoploidy, and hybridization at tetraploid level) of gp. Andigena.—Most of the electromorphs of gp. Tuberosum were also found in gp. Andigena; both the direct derivation of that group from the Andean tetraploid potatoes and the repeated introgression provided by breeding programmes could explain this result. However, the allele c of Pgm-B, present in 30 out of 76 Tuberosum cultivars from Northern Hemisphere as well as in 3 Chilean Tuberosum cultivars, lacks in the 258 Andigena genotypes sampled, suggesting that Chilean germplasm could have taken part in the origin of at least the 39% of the potato cultivars from Europe and North America analyzed here.—The distanceWagner procedure provides an estimate of a 30% of heterogeneity in the evolutionary divergence shown by different groups of cultivated potatoes. Diploid groups show a higher (22.5%) evolutionary rate than tetraploids, which can be attributed to both tetrasomic inheritance and facultative autofecundation that exists in Andigena and Tuberosum groups. Thus, artificial selection acting since 10000 years has not resulted in a higher rate of molecular evolution at the isozyme level in the tetraploids.     

In Vitro Study of Mitochondrial Protein Synthesis during Mitochondrial Biogenesis in Excised Plant Storage Tissue

Mitochondrial biogenesis was induced in Jerusalem artichoke (Helianthus tuberosus) tuber by aging tissue discs in distilled water for up to 26 hours. Changes in the purified mitochondrial fraction during aging included an increase in both protein content and specific respiratory activity. Using intact isolated mitochondria, conditions were optimized for incorporation of radioactive amino acid into protein. Incorporation was dependent upon the supply of an oxidizable substrate or an external ATP-generating system and showed characteristic sensitivity to inhibitors of protein synthesis. Aging of the tissue resulted in a 3-fold increase in the rate of in vitro incorporation of [³⁵S]methionine into mitochondrial protein. An analysis of the free amino acid pool in the mitochondrial fraction showed that the decrease in methionine level during aging of intact tissue was sufficient to account for the increased rate of protein labeling. The activation of mitochondrial biogenesis which occurs after slicing is not dependent on an increase in the capacity of mitochondria to synthesize protein as assayed in vitro.     

Epidermal and seed surface characters of plants: systematic applicability and some evolutionary aspects

Based on SEM examinations of about 5000 species of seed plants, this is a survey of their epidermal surface characters with an aim to application in taxonomy. Surface characters may be grouped into four categories: (1) Cellular arrangement or cellular pattern. (2) Shape of cells (the "primary sculpture" of a surface). (3) Relief of outer cell walls (the "secondary sculpture" superimposed on the primary sculpture), caused mainly by cuticular striations and superficially visible wall inclusions and wall thickenings. (4) Epicuticular secretions (the "tertiary sculpture" superimposed on the secondary sculpture), i.e. mainly waxes and related substances.
The systematic applicability is discussed for each of these structural groups. Epidermal characters are only slightly influenced by environmental conditions. Their high structural diversity provides most valuable criteria for the classification between species and family level. There is also some evidence for their systematic applicability above the family level.
The possible evolutionary–ecological significance of surface sculpturing is discussed briefly. There is evidence that these features may be seen primarily under the aspects of reduced ability of plants to contaminate and as temperature control mechanisms of the surfaces.     

Morphological and cytochemical alterations of the Golgi apparatus and GERL in rat parotid acinar cells during ethionine intoxication and recovery

The present electron microscopic cytochemical investigation was undertaken to characterize the alterations in the golgi apparatus and GERL of rat parotid acinar cells during ethionine intoxication and recovery. Although the Golgi apparatus and GERL were reduced in size, and some broadening of the Golgi saccules occurred as the result of ethionine treatment, the relative localization of thiamine pyrophosphatase (TPPase) activity in the Golgi saccules, and acid phosphatase activity (AcPase) in GERL, remained unchanged. Shortly after ethionine treatment was stopped, a dramatic redistribution of enzyme activities was noted. Within the first 24 hours of recovery, the Golgi apparatus began to enlarge, and the content of secretory granules increased. By day 3 of recovery, cisternae morphologically identifiable as GERL and forming secretory granules possessed TPPase activity, while AcPase activity was virtually undetectable. After seven days of recovery, the Golgi apparatus and GERL appeared both morphologically and cytochemically normal. The enzyme modulation observed during recovery may be correlated with increased secretory granule production. Furthermore, the presence of TPPase activity in GERL and forming secretory granules lends support to the suggestion that GERL may be derived from the trans Golgi saccule.     

Repeated characterization, analysis of variance limitation and discrimination analysis classification of EEG-activity patterns in human sleep]

1. To describe quantitatively and to deliminate nine EEG sleep patterns, mean values and standard deviations of abundances of the frequencies 0.8 ... 1.8 c/sec, 2...3.5 c/sec, 4...13c/sec, 14 to 17 c/sec, 18 to 22 c/sec, and 23 to 40 c/sec as well as of the average amplitudes in selected frequency ranges were calaculated and the distributions represented. 2. All nine EEG activity patterns could be separated by means of univariate and multivariate analyses of variance on the basis of all 28 as well as the 17 indispensable variables. 3. In the course of a stepwise reduction of variables within the framework of a linear discriminant analysis an optimal set of 17 variables was determined for the separation of the patterns, comprising: the percent quantity of the frequencies 0.8 ... 3.5 c/sec, 7 ... 9 c/sec and 18 to 40 c/sec as well as the average amplitudes in the frequency ranges 0.8 to 3.5 c/sec and 7.5 to 40 c/sec. 4. By linear regression analyses it could be shown that the sleep scording system used, can be reflected on an interval scale with the aid of discriminant functions; this can be achieved on the basis of the optimal set of variables as well as of the five most indispensable variables. 5. Finally the degree of the objectivity of the scoring procedures was demonstrated. Advantages and disadvantages of sleep scoring systems were discussed and possibilities of the utilization of results suggested, also in respect to the further development of the automatic recognition of EEG activity patterns.     

Distribution of receptors and functions on cell surfaces: quantitation of ligand-receptor mobility and a new model for the control of plasma membrane topography

The long-range movements of membrane ligand-receptor complexes into surface caps and into the pseudopods of cells performing phagocytosis, the uropods of motile cells and the cleavage furrows of dividing cells appear to be analogous processes. A common mechanism to explain these movements must take into account several recent observations. First, laser photobleaching studies have indicated that Concanavalin A-receptor movement occurs unidirectionally; and analyses of Con A redistribution by quantitative video intensification microscopy (QUAVIM) have shown that movement may exceed the maximum rates measured for protein diffusion in membranes. These are the results predicted for a process of directed migration but not for a process of diffusion with entrapment. In addition it has been found that membrane receptors may segregate out of as well as into cap, pseudopod, uropod and cleavage furrow regions and that topographical heterogeneity on asymmetric cells is not restricted to membrane molecular determinants but extends to a range of endocytic functions and to a macromolecular complex, the coated pit. All dynamic surface events are arrested during mitosis. A new model for the regulation of plasma membrane topography has been developed from these diverse quantitative, functional and morphological data. Its essence is the entrainment of selected membrane determinants on membrane waves directed towards regions such as caps, pseudopods, uropods and cleavage furrows. The waves are initiated by tension due to asymmetric microfilament-membrane interaction.     

Cytogenetic and electrophoretic evidence for a polyploid origin of the basic chromosome number x = 14 in the genusAsphodelus (Liliaceae)

Cytogenetic and electrophoretic analyses on 2n = 28 strains ofAsphodelus cerasiferus strongly suggest that the basic number x = 14 of the genusAsphodelus is of secondary polyploid origin from x = 7.     

Isolation and maintenance of differentiated exocrine gland acinar cells in vitro

Summary Methods have been developed for isolating and maintaining differentiated rat exorbital lacrimal, parotid, and pancreatic acinar cells for up to 1 month in culture. The dissociated cells retained their differentiated morphology when cultured as suspension cultures at 35°C with the appropriate secretagogue (exorbital lacrimal, 10⁻⁶ M carbamyl choline; pancreas 10⁻⁵ M carbamyl choline; parotid, 10⁻⁶ M isoproterenol). Under these conditions the cells remained viable and differentiated for up to 4 weeks in culture and continued to incorporate³H-leucine at rates similar to those of freshly isolated cells. If secretagogue was omitted from the medium, the cells rapidly degenerated. These results indicate that differentiated from the medium, the cells rapidly degenerated. These results indicate that differentiated exocrine gland acinar cells may be maintained in vitro and utilized as a model system for the study of secretory processes.