BackgroundSeveral studies have shown that genomes can be studied via a multifractal formalism. Recently, we used a multifractal approach to study the genetic information content of the Caenorhabditis elegans genome. Here we investigate the possibility that the human genome shows a similar behavior to that observed in the nematode.ResultsWe report here multifractality in the human genome sequence. This behavior correlates strongly on the presence of Alu elements and to a lesser extent on CpG islands and (G+C) content. In contrast, no or low relationship was found for LINE, MIR, MER, LTRs elements and DNA regions poor in genetic information. Gene function, cluster of orthologous genes, metabolic pathways, and exons tended to increase their frequencies with ranges of multifractality and large gene families were located in genomic regions with varied multifractality. Additionally, a multifractal map and classification for human chromosomes are proposed.ConclusionsBased on these findings, we propose a descriptive non-linear model for the structure of the human genome, with some biological implications. This model reveals 1) a multifractal regionalization where many regions coexist that are far from equilibrium and 2) this non-linear organization has significant molecular and medical genetic implications for understanding the role of Alu elements in genome stability and structure of the human genome. Given the role of Alu sequences in gene regulation, genetic diseases, human genetic diversity, adaptation and phylogenetic analyses, these quantifications are especially useful.

The genetic variation and population structure of three populations of Anopheles darlingi from Colombia were studied using random amplified polymorphic markers (RAPDs) 001). The F ST distances and AMOVAs using AFLP loci support the differentiation of the Guyana biogeographic province population from those of the Chocó-Magdalena. In this last region, Chocó and Córdoba populations showed the highest genetic flow.Key words: amplified fragment length polymorphism -Anopheles darlingi -genetic diversity -malaria vectors -random amplified polymorphic DNA -polymerase chain reaction -ColombiaAnopheles darlingi is recognized as the most anthropophillic and endophagous species of Anopheles in the Americas (Fleming 1986), the primary malaria vector in the Neotropics (Conn et al. 2001), and is considered the most important malaria vector in the Amazon Basin . It is most frequently found in the hot and humid lowlands, with a discontinuous distribution from Southern Mexico to Northern Argentina, but not reported in Costa Rica, Nicaragua, and Panama (Linthicum 1988, Manguin et al. 1999. In Colombia, it is found up to an altitude of 450 m in the premontane zone of the Andes (Fleming 1986), which is characterized by three large mountain ranges and variety of geographic features ( Fig. 1) that clearly separate the eastern from the western regions and possibly limit the free gene flow between these regions.Based on the original description of An. darlingi by Root (1926), phenotypic variation and differences in hematophagous behavior have contributed to generating a certain degree of confusion regarding its specific taxonomic status (Galvão et al. 1937, Galvão & Barreto 1938, Galvão 1940, Linthicum 1988, Rubio-Palis 1998. Given the foregoing and the great importance of this species, a series of population studies were conducted, using morphological and molecular tools (Manguin 1999), oriented toward clarifying both taxonomic status and genetic structure within its range of distribution. Lounibos and Conn (2000) recently reviewed the use of molecular markers in the study of the ecology and genetics of An. darlingi. Its biting behavior was summarized by Rosa-Freitas et al. (1992), andZimmerman (1992) demonstrated great variability in post-blood feeding/resting behavior. Depending on the region of study, one, two, and even three peaks of major biting activity have been observed, as well as variation in the extension or time interval of peak hematophagous activity. Hudson (1984) and Klein and Lima (1990) suggest that this indicates the existence of a species complex. Nevertheless, from morphological studies did not reveal substantial differences among populations throughout the area of distribution, including populations in isolated zones (Linthicum 1988, Rubio-Palis 1998, Manguin et al. 1999. According to Linthicum (1988) the diagnostic characters are very constant, even for the Guatemalan and Honduran populations and interpopulational variation is almost equal to intrapopulational variation.Additionally, several studies on this spe...

Ulmus glabra Hudson, or Wych elm, occurs as fragmented and relict natural populations in the Central System, which acts as a refugium in the Iberian Peninsula. Considering the importance of the Central System populations of U. glabra, the main objective was to assess their genetic diversity using nuclear microsatellite markers. A total of 360 different genotypes were detected in the 427 U. glabra individuals analyzed. Wych elm populations showed a highly significant genetic differentiation (24%; p = 0.0001). Of the 22 populations studied, population of Rozas de Puerto Real (ROZ) showed the highest values of effective number of alleles (2.803), mean Shannon's diversity (1.047) and expected heterozygosity (0.590). Populations of ROZ and Mombeltrán (MOM) showed the highest values of observed heterozygosity (0.838 and 0.709, respectively), and highly negative values for inbreeding coefficient (−0.412 and −0.575, respectively). Also, most of putative hybrids (50 of 55) were observed in these two populations. Demographic analysis revealed signals for recent (four populations) and ancestral (fifteen populations) bottlenecks. Fragmented populations with diminishing number of individuals, along with anthropogenic intervention and Dutch elm disease (DED), are the main threats to U. glabra populations. From a future perspective, the information generated can be considered in the formulation of conservation strategies for U. glabra populations in the Central System.

Analysis of two samples of the oil of Acinus alpinus (L.) Moench subsp. meridionalis (Nyman) P. W. Ball revealed the following composition: monoterpene hydrocarbons (6.1 70, 14.1%), oxygenated monoterpenes (1.7%. 1.9"/0), sesquiterpene hydrocarbons (83.1%, 79.3%) and oxygenated sesquiterpenes (9.1Y0, 4.7%). The main constituents found were germacrene-D (56.8%, 43.2%), rram-p-caryophyllene (6.2%, 15.4%) and bicyclogermacrene (s.90/,, 11.7%). KEY WORDS Acinus alpinus ( L . ) Moench subsp. meridionalis (Nyman) P. W. Ball Lamiaceae Volatile oil Sesquiterpenes Germacrene-D tram-p-Caryophyllene Bicyclogermacrene.

Sclerosing adenocarcinoma of the extrahepatic bile duct and pyometra were diagnosed in a 17-year-old entire female Siamese cat which had had anorexia, depression, acute icterus and abdominal distension for about a week. Clinical signs derived from he tumor were minimal and non-specific until the diffuse thickening of the bile duct obstructed bile flow and acute icterus resulted. Sclerosing adenocarcinoma of the extrahepatic bile duct is a human variant of bile duct carcinomas that has not, to the authors' knowledge, previously been described in the cat, but it appears to be as invasive as other feline hepatic tumours.