Regulation of Apterous activity in Drosophila wing development.

Apterous is a LIM-homeodomain protein that confers dorsal compartment identity in Drosophila wing development. Apterous activity requires formation of a complex with a co-factor, Chip/dLDB. Apterous activity is regulated during wing development by dLMO, which competes with Apterous for complex formation. Here, we present evidence that complex formation between Apterous, Chip and DNA stabilizes Apterous protein in vivo. We also report that a difference in the ability of Chip to bind the LIM domains of Apterous and dLMO contributes to regulation of activity levels in vivo.     

Replication banding in the chromosomes of the European eel (Anguilla anguilla)

The chromosomes of the European eel Anguilla anguilla have been analyzed with a replication banding technique from lymphocyte cultures treated with 5-BrdU. This technique allows us to identify with high resolution the individual chromosome pairs and to differentiate classes of chromatin by the order of replication. The replication banding obtained on the chromosomes of European eel can be related with the structural bands described in this species.     

Impact of sar and agr on methicillin resistance in Staphylococcus aureus

Abstract The global regulators agr and sar control expression of cell wall and extracellular proteins. Inactivation of either sar and/or agr in a typical heterogeneously methicillin-resistant Staphylococcus aureus resulted in a small but reproducible decrease in the number of cells in the subpopulation expressing high methicillin resistance. The amount of low affinity penicillin-binding protein PBP2', the prerequisite for methicillin resistance, was apparently not affected, however, a reduction in PBP1 and PBP3 production was observed, suggesting that these resident PBPs of the cells might be involved somehow together with PBP2' in high level methicillin resistance.     

Establishment of transformed root cultures of Perezia cuernavacana producing the sesquiterpene quinone perezone

Summary The sesquiterpene quinone currently known as perezone is abundantly produced by the roots of Perezia cuernavacana. This compound is of biotechnological interest since it may be used as a pigment and has several pharmacological properties. In this work we demonstrate that perezone is also produced in transformed root cultures of P. cuernavacana. Hairy roots were induced by inoculation of internodal segments of sterile plants of P. cuernavacana with Agrobacterium rhizogenes AR12 strain. The axenic liquid MS medium cultures of the hairy roots isolated from the internodes showed active growth in the absence of growth regulators. The transformed nature of the tissue was confirmed by genomic integration (PCR and slot blot hybridization) and expression (enzyme activity) of the marker gus-gene. The production of perezone by a transformed root culture was evidenced by IR spectroscopy. Our results offer an alternative for enhanced production of perezone and represent an advantage over its extraction from natural plant populations which present problems in their agronomic culture.     

Rhizobium extracellular structures in the symbiosis

The extracellular and surface polysaccharides produced by Rhizobium species constitute a composite macromolecular interface between the bacterial cell and its environment. Several of these polysaccharides are involved in the complex series of interactions leading to the establishment of an effective Rhizobium-legume symbiosis. Extracellular heteropolysaccharides (EPSs) are found in culture supernatants, while capsular polysaccharides adhere to the cell surface. Cyclic (1–2)--d glucan is a periplasmic oligosaccharide that has also been found in the culture supernatants of some strains. The lipopolysaccharides (LPSs), which form part of the outer membrane and contain the O-somatic antigens, comprise the other major group of extracellular polysaccharides. In this review we will describe the major Rhizobium extracellular structures and their role in symbiosis with leguminous plants.The authors are with the Departamento de Microbiologia y Parasitologia, Facultad de Farmacia. Universidad de Sevilla, 41012 Sevilla, Spain     

Isolation of somatic hybrids by cloning Nicotiana heterokaryons in nurse cultures

Fusion of Nicotiana knightiana Goodsp. and kanamycin resistant Nicotiana sylvestris Speg. et Com. protoplasts was induced by polyethylene glycol treatment. Heterokaryons were isolated by micropipette and transferred to nurse cultures of albino cells. Colonies originating from the heterokaryons could subsequently be distinguished by their green colour. The somatic hybrid nature of four such colonies was confirmed by isoenzyme pattern, kanamycin resistance and restored morphogenic potential. An additional kanamycin resistant line with characteristic Nicotiana knightiana isoenzymes was also found indicating that the drug resistance in the kanamycin resistant parent is under cytoplasmic control.Abbreviations ADH alcohol dehydrogenase - Nk Nicotiana knightiana     

First record of Crustacea Malacostraca from fresh waters in the Canary Islands

Crustacea Malacostraca were hitherto unknown from fresh waters of the Canary Islands. A new species of Amphipoda, Rhipidogammarus rheophilus, has recently been discovered in springs and spring brooks in Tenerife.

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Resumen Crustacea Malacostraca era hasta ahora desconocida de las aguas dulces de las Islas Canarias. Una nueva especie de anfípodo, Rhipidogammarus rheophilus, ha sido recientemente descubierto de fuentes y manantiales de Tenerife.

     

Chromosome and nucleotide sequence differentiation in genomes of polyploid Triticum species

Summary The nature of genome change during polyploid evolution was studied by analysing selected species within the tribe Triticeae. The levels of genome changes examined included structural alterations (translocations, inversions), heterochromatinization, and nucleotide sequence change in the rDNA regions. These analyses provided data for evaluating models of genome evolution in polyploids in the genus Triticum, postulated on the basis of chromosome pairing at metaphase I in interspecies hybrids.The significance of structural chromosome alterations with respect to reduced MI chromosome pairing in interspecific hybrids was assayed by determining the incidence of heterozygosity for translocations and paracentric inversions in the A and B genomes of T. timopheevii ssp. araraticum (referred to as T. araraticum) represented by two lines, 1760 and 2541, and T. aestivum cv. Chinese Spring. Line 1760 differed from Chinese Spring by translocations in chromosomes 1A, 3A, 4A, 6A, 7A, 3B, 4B, 7B and possibly 2B. Line 2541 differed from Chinese Spring by translocations in chromosomes 3A, 6A, 6B and possibly 2B. Line 1760 also differed from Chinese Spring by paracentric inversions in arms 1AL and 4AL whereas line 2541 differed by inversions in 1BL and 4AL (not all chromosomes arms were assayed). The incidence of structural changes in the A and B genomes did not coincide with the more extensive differentiation of the B genomes relative to the A genomes as reflected by chromosome pairing studies.To assay changing degrees of heterochromatinization among species of the genus Triticum, all the diploid and polyploid species were C-banded. No general agreement was observed between the amount of heterochromatin and the ability of the respective chromosomes to pair with chromosomes of the ancestral species. Marked changes in the amount of heterochromatin were found to have occurred during the evolution of some of the polyploids.The analysis of the rDNA region provided evidence for rapid fixation of new repeated sequences at two levels, namely, among the 130 bp repeated sequences of the spacer and at the level of the repeated arrays of the 9 kb rDNA units. These occurred both within a given rDNA region and between rDNA regions on nonhomologous chromosomes. The levels of change in the rDNA regions provided good precedent for expecting extensive nucleotide sequence changes associated with differentiation of Triticum genomes and these processes are argued to be the principal cause of genome differentiation as revealed by chromosome pairing studies.     

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.