Oxygen inhibition of nitrate uptake is a general regulatory mechanism in nitrate respiration

It has recently been demonstrated that oxygen inhibits nitrate uptake by denitrifying Pseudomonas aeruginosa. The purpose of the present investigation was to determine if this novel mechanism of regulation is universal for the regulation of nitrate respiration in other widely divergent species of bacteria. Nitrate transport by whole cell suspensions was completely and reversibly inhibited in 11 out of 12 species tested, whereas nitrate reduction by cell-free extracts was not affected by oxygen or was only partially inhibited in some cases. These results indicate that oxygen inhibition of nitrate uptake is a general regulatory phenomenon.     

Two new species of gorgonian octocorals from the Tropical Eastern Pacific Biogeographic Region (Cnidaria,Anthozoa, Gorgoniidae)

The gorgoniid Eugorgia is exclusively an eastern Pacific genus. It has a wide geographic and bathymetric range of distribution, found from California to Perú and extends down to 65 m deep. Two new species are herein described. The morphological characters were analyzed and illustrated by light and scanning electron microscopy. Eugorgia beebei sp. n. can be distinguished by its white, ascending, sparse colony growth. Eugorgia mutabilis sp. n. can be distinguished by its white colony that changes color after collection, and the conspicuous sharp-crested disc sclerites. From a morphological point of view the new species are related to the daniana-group, the rubens-group and the siedenburgae-group of Eugorgia; their affiliations, and the proposal of a new group are discussed. These new species increases the number of species in the genus to 15, and contribute to the knowledge of the eastern Pacific octocoral biodiversity.     

CHARACTER DISCRIMINATORY POWER,CHARACTER-SET CONGRUENCE,AND THE CLASSIFICATION OF INDIVIDUALS FROM HYBRID ZONES: AN EXAMPLE USING STONE CRABS (MENIPPE)

Many investigators categorize individuals from hybrid zones to facilitate comparisons among genotypic classes (e.g., parental, F₁, backcross) for comparative studies in which components of fitness or geographic variation are being analyzed. Frequently, multiple character sets representing genetically independent traits are used to classify these individuals and various methodologies are employed to combine the classifications obtained from the different character sets. We adapted the principles of total evidence and taxonomic congruence (two formalized approaches used by systematists in formulating phylogenetic hypotheses) to address the problem of discriminating hybridizing species and classifying individuals from hybrid zones. As our model, we used two morphological (coloration and morphometric) and two molecular (allozyme and mitochondrial DNA restriction-fragment-length polymorphism) character sets that differentiate two stone crab species (Menippe adina and M. mercenaria). Using principal-components analysis, we determined that combining character sets and eliminating characters or character sets that did not have large eigenvector coefficients for the principal component that best separated the two species yielded the highest level of discrimination between species and allowed us to classify a broad range of morpho-genotypes as hybrids. For the stone crabs, three diagnostic allozyme loci and five diagnostic coloration characters best separated the species. The two character sets were not completely congruent, but they agreed in their classification of 50% of the individuals from the hybrid zone and rarely strongly disagreed in their classifications. Classification discrepancies between the two character sets probably represent variation between traits in interspecific gene flow rather than intraspecific, ecologically mediated variation. Our results support the assertions of previous investigators who espoused the benefits associated with using multiple character sets to classify individuals from hybrid zones and demonstrate that, if character sets are reasonably congruent and numerically balanced, combining diagnostic characters from multiple character sets (a total-evidence approach) can enhance discriminatory power between species and facilitate the assignment of hybrid-zone individuals to genotypic classes. On the contrary, classifying hybrid-zone individuals using character sets separately (a taxonomic-congruence approach) provides the opportunity to compare levels of introgression between species and to assess reasons for discordance among the data sets.     

Factors influencing the efficiency of T-DNA transfer during co-cultivation of Antirrhinum majus with Agrobacterium tumefaciens

Summary The effects of varying the pH of the cocultivation medium, additons of vir-inducing phenolic compounds and the strains of wild-type agrobacteria on transformation rates of a number of different varieties of Antirrhinum majus were studied. In general, optimal transformation was found with strains C58 or A281 and was favoured by low pH and the inclusion of acetosyringone in the co-cultivation medium. However, maximal transformation of the least susceptible variety was achieved at high pH and in the presence of syringaldehyde. This demonstrates the need for the optimization of a wide range of culture conditions when working with new genotypes and offers a rational approach towards the development of Agrobacterium-mediated transformation of new species or varieties.Abbreviations BAP 6-benzylaminopurine - MS Murashige and Skoog medium (Murashige and Skoog, 1962) - NOA naphthoxyacetic acid     

Potential long-acting contraceptive agents: esters of testosterone with alkoxy- and halogeno-substituted carboxylic acids

The chemical synthesis and physical data of several new esters of testosterone (17 beta-hydroxyandrost-4-en-3-one), which contain either a halogeno or an alkoxy substituent in the acid chain, are reported.     

Alterations of class I HLA genes in human colon cancers

Summary Alterations of HLA class I genes were found in 3 of 12 human colon cancers. Rearrangements in HLA class I genes were observed in 2 cancers and amplification of HLA-coding genes was observed in 1 cancer. All 3 cancers were at an advanced stage. No examples of amplification or rearrangement in the HLA genes were found in 10 other tumours of diverse types. No alterations in the ₂-microgubulin gene were observed in 22 human solid tumours included in this study. The association between alterations in HLA genes and proto-oncogenes in these tumours is discussed.     

Phencyclidine (PCP) injected in the nucleus accumbens increases extracellular dopamine and serotonin as measured by microdialysis

Phencyclidine (PCP; 20 micrograms in 0.5 microliter) was tested by local brain injection for neurochemical effects in the nucleus accumbens and striatum of rats. Changes in dopamine turnover could not be detected in postmortem tissue assays. In contrast, extracellular levels of dopamine significantly increased as measured by microdialysis in freely moving animals. PCP also increased extracellular levels of serotonin and decreased 3,4-dihydroxyphenylacetic acid (DOPAC), but did not change homovanillic acid (HVA) or 5-hydroxyindoleacetic acid (5HIAA). Microdialysis suggests that PCP acts in some dopamine terminal regions to increase extracellular dopamine and serotonin.     

Brain blotting: a method to detect multiple DNA copies in specific brain regions

We developed a method to detect multiple DNA copies (both cellular and viral) in specific brain regions by blotting thick frozen sections onto nylon membranes. This was achieved by "printing" the frozen sections on standard blotting paper immediately after cryotome sectioning and performing blotting according to the standard Southern technique. A "replica" of the blotted section was obtained by keeping on the glass slide the next frozen section cut, which was then stained for conventional histopathological analysis and the cell nuclei counted to give an estimate of the total amount of DNA present in each section. The blotted membranes were then denatured and hybridized with a nick-translated Alu probe either at 42 degrees C with 50% formamide or at 68 degrees C without formamide. Brain sections from mice infected with Herpes simplex virus 1 (HSV1), blotted and hybridized with a nick-translated HSV1 probe, clearly showed the focal nature of the Herpes simplex infection, which was also demonstrated immunohistologically using a virus specific antiserum. This method of DNA detection, conveniently modified, might also be used to detect nuclear and cytoplasmic RNAs in specific coronal sections of whole brain before localization at high power by standard in situ techniques.