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.     

Interferon production and tumor cell killing by human lymphocytes stimulated in mixed-lymphocyte culture

The in vitro synthesis of interferon (IFN) by human lymphocytes stimulated in mixed-lymphocyte culture (MLC) was examined. The production of IFN in MLC was restricted to T lymphocytes and maximum levels of IFN were detected in supernatants from cells incubated for 5 to 7 days. The IFN produced was identified as IFN-gamma by antibody neutralization. To identify the T cell responsible for IFN production, purified T lymphocytes were separated into subpopulations after incubation in 5 mM theophylline. Theophylline-resistant (T-res) T cells retain the ability to form sheep erythrocyte (SRBC) rosettes and are depleted in IgG Fc receptor-positive T cells (T gamma cells). Theophylline-sensitive (T-sens) T cells fail to form rosettes after theophylline treatment and are enriched in T gamma cells. In addition, analyses using monoclonal antibodies showed that T-sens cells were enriched in OKM1-, HNK-1-, and 7.2-positive cells and T-res cells contained increased numbers of 9.6- and OKT4-positive cells. Following MLC stimulation, equivalent levels of IFN-gamma were produced by T-res and T-sens cells and both subpopulations maintained natural killer (NK)-like cytotoxicity against K562 target cells. Addition of partially purified IFN-gamma to unstimulated T-res and T-sens cells resulted in the maintenance of NK-like cytotoxicity in a manner analogous to that observed after MLC. Additional experiments indicated that peripheral blood lymphocytes depleted of 9.6- or OKM1-positive cells by complement-mediated lysis were devoid of cytotoxicity against K562 cells. Furthermore, MLC stimulation of 9.6- or OKM1-depleted cells failed to restore cytotoxic activity. In summary, these experiments demonstrate that the maintenance of NK-like cytotoxicity by MLC-stimulated T cells is associated with the synthesis of IFN-gamma, that MLC stimulated T-res and T-sens T-cell subsets produce equivalent amounts of IFN, and that 9.6- or OKM1-positive cells are required for the maintenance of NK-like cytotoxicity in MLC.     

The neurotrophic factors brain-derived neurotrophic factor and neurotrophin-3 are ligands for the trkB tyrosine kinase receptor.

Neurotrophic factors are essential for neuronal survival and function. Recent data have demonstrated that the product of the tyrosine kinase trk proto-oncogene binds NGF and is a component of the high affinity NGF receptor. Analysis of the trkB gene product, gp145trkB, in NIH 3T3 cells indicates that this tyrosine kinase receptor is rapidly phosphorylated on tyrosine residues upon exposure to the NGF-related neurotrophic factors BDNF and NT-3. Furthermore, gp145trkB specifically binds BDNF and NT-3 in NIH 3T3 cells and in hippocampal cells, but does not bind NGF. Thus, the trk family of receptors are likely to be important signal transducers of NGF-related trophic signals in the formation and maintenance of neuronal circuits.     

Ca2+ calmodulin-dependent protein kinase activity in the ascomycetes Neurospora crassa

DEAE-cellulose column chromatography of Neurospora crassa soluble mycelial extracts leads to the resolution of three major protein kinase activity peaks designated PKI, PKII, and PKIII.PKII activity is stimulated by Ca²⁺ and Neurospora or brain calmodulin. Maximal stimulation was observed at 2 µM-free Ca²⁺ and 1 µg/ml of the modulator. The stimulatory effect of the Ca²⁺-calmodulin complex was blocked by EGTA and by some calmodulin antagonists such as phenothiazine drugs or compound 48/80.PKII phosphorylates different proteins, among which histone II-A at a low concentration and CDPKS, the synthetic peptide specific for Ca²⁺-calmodulin dependent protein kinases, are the best substrates. Some phosphorylation can be detected in the absence of any exogenous acceptor. PKII activity assayed in the presence of histone II-A or in the absence of exogenous phosphate acceptor (autophosphorylation) co-elute in a DEAE-cellulose column at 0.28 M NaCl. As result of the autophosphorylation reaction of the purified enzyme a main phosphorylated component of 70 kDa was resolved by SDS-polyacrylamide gel electrophoresis. It is possible that this component is an active part of this enzyme.