Climate and growth form: the consequences for genome size in plants.

The adaptive significance of nuclear DNA variation in angiosperms is still widely debated. The discussion mainly revolves round the causative factors influencing genome size and the adaptive consequences to an organism according to its growth form and environmental conditions. Nuclear DNA values are now known for 3874 angiosperm species (including 773 woody species) from over 219 families (out of a total of 500) and 181 species of woody gymnosperms, representing all the families. Therefore, comparisons have been made on not only angiosperms, taken as a whole, but also on the subsets of data based on taxonomic groups, growth forms, and environment. Nuclear DNA amounts in woody angiosperms are restricted to less than 23.54 % of the total range of herbaceous angiosperms; this range is further reduced to 6.8 % when woody and herbaceous species of temperate angiosperms are compared. Similarly, the tropical woody dicots are restricted to less than 50.5 % of the total range of tropical herbaceous dicots, while temperate woody dicots are restricted to less than 10.96 % of the total range of temperate herbaceous dicots. In the family Fabaceae woody species account for less than 14.1 % of herbaceous species. Therefore, in the total angiosperm sample and in subsets of data, woody growth form is characterized by a smaller genome size compared with the herbaceous growth form. Comparisons between angiosperm species growing in tropical and temperate regions show highly significant differences in DNA amount and genome size in the total angiosperm sample. However, when only herbaceous angiosperms were considered, significant differences were obtained in DNA amount, while genome size showed a non-significant difference. An atypical result was obtained in the case of woody angiosperms where mean DNA amount of tropical species was almost 25.04 % higher than that of temperate species, which is because of the inclusion of 85 species of woody monocots in the tropical sample. The difference becomes insignificant when genome size is compared. Comparison of tropical and temperate species among dicots and monocots and herbaceous monocots taken separately showed significant differences both in DNA amount and genome size. In herbaceous dicots, while DNA amount showed significant differences the genome size varies insignificantly. There was a non-significant difference among tropical and temperate woody dicots. In three families, i.e., Poaceae, Asteraceae, and Fabaceae the temperate species have significantly higher DNA amount and genome size than the tropical ones. Woody gymnosperms had significantly more DNA amount and genome size than woody angiosperms, woody eudicots, and woody monocots. Woody monocots also had significantly more DNA amount and genome size than woody eudicots. Lastly, there was no significant difference between deciduous and evergreen hardwoods. The significance of these results in relation to present knowledge on the evolution of genome size is discussed.

Nuclear DNA amounts in 112 species of tropical hardwoods -- new estimates.

The 4C DNA values of 112 species, belonging to 37 families have a range from 0.83 pg (Bixa orellana) to 15.54 pg (Thryallis angustifolia), showing a 18.72-fold variation. The genome size varies from 0.21 pg (Bixa orellana) to 3.32 (Thespesia populnea), with a 15.8-fold difference. The Bombacaceae has the minimum range (1.08-fold) of variation, while the maximum (5.0-fold) is shown by the Fabaceae. The Boraginaceae, Lauraceae, Malpighiaceae, and Malvaceae generally have higher 4C DNA values of > 10 pg, while the Bixaceae, Caricaceae, Oxalidaceae, and Santalaceae have lower values of < 2.0 pg. These data add further to our knowledge on variation in DNA amount in tropical hardwoods.

Hymenoptera sting anaphylactic reactions in the Mediterranean population of Albania.

BACKGROUND: Relatively few studies have examined the relation of different hymenoptera sting reactions. OBJECTIVE: To investigate the relation of anaphylactic reactions against stings of different hymenoptera subspecies in the Mediterranean population of Albania. MATERIALS AND METHODS: A retrospective study was conducted using the clinic files of 111 patients who were diagnosed for hymenoptera sting reactions from 1987 to 1996. Antigens used consisted of purified hymenoptera venom (bee, wasp, and paperwasp). The patients were diagnosed by intracutaneous tests in concentrations of 0.001 microgram/ml, 0.01 microgram/ml, 0.1 microgram/ml, and 1 microgram/ml. RESULTS: The median age of the patients was 27 years. 57% of stings occurred between 20 to 40 years of age. The majority of anaphylactic reactions were recorded during the months of June to October, 81% of the patients were admitted to the hospital due to Mueller grade II to III reactions. In 26% of all cases, crossreactions (bee-wasp 16%, bee-wasp-paperwasp 7%, wasp-paperwasp 2%, bee-paperwasp 1%) were found. Of all anaphylactic reactions, 64% were attributed to bees, 24% to wasps, 8% to both bees and wasps, and 2% to paperwasps. CONCLUSIONS: In contrast to industrialized countries such as the United States or Western Europe where urban populations predominate, reactions to bee venom were more prevalent in the present study population.

Development of flow cytogenetics and physical genome mapping in chickpea (Cicer arietinum L.).

Procedures for flow cytometric analysis and sorting of mitotic chromosomes (flow cytogenetics) have been developed for chickpea (Cicer arietinum). Suspensions of intact chromosomes were prepared from root tips treated to achieve a high degree of metaphase synchrony. The optimal protocol consisted of a treatment of roots with 2 mmol/L hydroxyurea for 18 h, a 4.5-h recovery in hydroxyurea-free medium, 2 h incubation with 10 micromol/L oryzalin, and ice-water treatment overnight. This procedure resulted in an average metaphase index of 47%. Synchronized root tips were fixed in 2% formaldehyde for 20 min, and chromosome suspensions prepared by mechanical homogenization of fixed root tips. More than 4 x 10(5) morphologically intact chromosomes could be isolated from 15 root tips. Flow cytometric analysis of DAPI-stained chromosomes resulted in histograms of relative fluorescence intensity (flow karyotypes) containing eight peaks, representing individual chromosomes and/or groups of chromosomes with a similar relative DNA content. Five peaks could be assigned to individual chromosomes (A, B, C, G, H). The parity of sorted chromosome fractions was high, and chromosomes B and H could be sorted with 100% purity. PCR on flow-sorted chromosome fractions with primers for sequence-tagged microsatellite site (STMS) markers permitted assignment of the genetic linkage group LG8 to the smallest chickpea chromosome H. This study extends the number of legume species for which flow cytogenetics is available, and demonstrates the potential of flow cytogenetics for genome mapping in chickpea.