Macroptilium (Benth.) Urban (Phaseoleae, Papilionoideae, Leguminosae) is an American genus of legumes, belonging to subtribe Phaseolinae along with other economically important genera, such as Vigna Savi and Phaseolus L. (the common bean genus). Cladistic analyses based on morphological, biochemical (storage seed proteins) and molecular (nuclear and plastid DNA sequences) data were performed on the 18 species currently ascribed to the genus, exploring several character weighting strategies. Equal weights, implied weighting and different transversion ⁄ transition costs were applied. The three data sets were first analyzed with separate partitions, and then combined into a single matrix. This study is the first one to analyze all the species of the genus from a cladistic point of view. In all the most parsimonious trees obtained, Macroptilium is monophyletic with excellent support values. Two monophyletic clades are recovered in almost all the analyses. Both are compound by nine species, and they constitute two sections of Macroptilium. Several interspecific relationships inside the genus are discussed.

RESUMEN(Citogenética evolutiva en Leguminosas americanas) Se presentan las características cromosómicas descriptas hasta el momento en Leguminosas americanas. A través del análisis de estos datos en conjunto con los morfológicos y las filogenias moleculares se proponen hipótesis acerca de los cambios cromosómicos ocurridos durante el proceso de divergencia y especiación de la familia. Los estudios cromosómicos indican una gran variación intergenérica, inter e intraespecífica, además de una amplia diversificación en el tamaño del genoma entre géneros, especies y poblaciones. A partir del número básico ancestral x=7 se deduce que la especiación híbrida poliploide ha sido muy importante en la diversificación de la familia. Por procesos de disploidía creciente y decreciente, tanto a nivel diploide como poliploide se originarían números básicos secundarios y series poliploides modificadas. En la parafilética subfamilia Caesalpinioideae habría predominado el proceso de disploidia decreciente de n=14 a n=11. En la monofilética subfamilia Mimosoideae, ocurrió un evento principal de evolución del número cromosómico de 14 a 13. Por último en Papilionoideae, la subfamilia más derivada de Leguminosae, se observó reducción del número básico de 14 a 7, pasando por números gaméticos de 11 y 8. Por otro lado, el origen recurrente de los poliploides y la ocurrencia de rearreglos intergenómicos, hibridación y poliploidía secundaria, son procesos que dificultan la agrupación natural de los taxones en algunos grupos de la familia Leguminosae. Palabras clave: Leguminosae, citogenética, poliploidía, evolución cromosómica, hibridación, América. ABSTRACT(Evolutionary cytogenetics in Americans Legumes) Chromosomic features described so far for Americans legumes are reviewed and analyzed, simultaneously with morphological and molecular characters. This is an invaluable opportunity to propose hypotheses about chromosome changes during the family divergence and speciation processes. The chromosome studies showed wide inter-generic, inter and intra-specific variability, as well as marked differences in genome sizes between genera, species and populations. By postulating an ancestral basic number of seven (x=7) it is possible to deduce that polyploid hybrid speciation was very important in the diversification of the family as a whole. Due to increasing and decreasing diploidy processes, secondary basic numbers and modified polyploids series could have arised both at diploid and polyploid levels. On the other hand, recurrent origin of polyploids, occurrence of inter-genomic rearrangements, hybridization and secondary polyploidy are all processes that make it difficult to group the taxa within the Leguminosae family in a natural sequence.

Prosopis L. is a rather primitive genus within the Leguminosae-Mimosoideae. This genus has been divided into five sections on the basis especially of the vegetative diversification of the spines. Three of the sections, Algarobia, Monilicarpa and Strombocarpa, are distributed in America. In order to elucidate systematic relationships between the American sections of Prosopis, a morphological and biochemical phylogeny were obtained. Twenty-two morphological characters were scored for 27 species of Prosopis and the outgroup taxon following polyacrilamide gel electrophoresis of seed storage proteins. The results obtained clearly prove that the secction Strombocarpa is a natural taxon. The section Algarobia, on the other hand, seems to comprise an artificial grouping of species. Members of the series Denudantes appear isolated from the remaining species, therefore this taxon should be treated as a new section within Prosopis. The section Algarobia should be circumscribed to series Chilenses, Ruscifoliae and Pallidae, which are always united in a monophyletic clade. Finally, no evidence was found to confirm the existence of the section Monilicarpa.

Enterotoxigenic Escherichia coli (ETEC) is a Gram-negative enteric pathogen that causes profuse watery diarrhea through the elaboration of heat-labile and/or heat-stable toxins. Virulence is also dependent upon the expression of adhesive pili and afimbrial adhesins that allow the pathogen to adhere to the intestinal epithelium or mucosa. Both types of enterotoxins are regulated at the level of transcription by cyclic AMP (cAMP) receptor protein (CRP). To further our understanding of virulence gene regulation, an in silico approach was used to identify putative CRP binding sites in the genome of H10407 (O78:H11), an ETEC strain that was originally isolated from the stool of a Bangledeshi patient with cholera-like symptoms circa 1971. One of the predicted binding sites was located within an intergenic region upstream of tibDBCA. TibA is an autotransporter and afimbrial adhesin that is glycosylated by TibC. Expression of the TibA glycoprotein was abolished in an H10407 crp mutant and restored when crp was provided in trans. TibA-dependent aggregation was also abolished in a cyaA::kan strain and restored by addition of exogenous cAMP to the growth medium. DNase I footprinting confirmed that the predicted site upstream of tibDBCA is bound by CRP. Point mutations within the CRP binding site were found to abolish or significantly impair CRP-dependent activation of the tibDB promoter. Thus, these studies demonstrate that CRP positively regulates the expression of the glycosylated afimbrial adhesin TibA through occupancy of a binding site within tibDBp.More than 100 genes in Escherichia coli and many other bacterial species are regulated by cyclic AMP (cAMP) receptor protein (CRP) through direct and indirect pathways (12,33,36,42,75,76). For CRP, DNA binding is cAMP dependent and the position of a CRP binding site relative to RNA polymerase largely determines whether it functions as an activator or a repressor of a particular gene or operon. With respect to the transcription start site, CRP binding sites centered at or near Ϫ62, Ϫ72, Ϫ83, or Ϫ93 are typical for class I CRPdependent promoters. Class II promoters have a binding site centered at or near Ϫ41. 5 (16, 24, 50). Class III promoters are more complex in that they usually require an additional transcription factor or multiple CRP binding sites (24). In comparison to class I and class II promoters, class III and CRPrepressed promoters display a greater range of binding site positions (33).In addition to regulating the expression of metabolic and housekeeping genes, CRP has been shown to regulate the expression of many virulence factors. For example, CRP positively regulates the expression of Pla, a surface-exposed protease of Yersinia pestis that is necessary for the establishment of primary pneumonic plague and facilitates dissemination of the bacterium during bubonic plague (46, 49). In Vibrio vulnificus, a marine bacterium that causes gastroenteritis when ingested with contaminated seafood, CRP positively regulates the expression of a cytolytic hemolysin and a he...