Niche divergence by deep‐sea octocorals in the genus Callogorgia across the continental slope of the Gulf of Mexico

Environmental variables that are correlated with depth have been suggested to be among the major forces underlying speciation in the deep sea. This study incorporated phylogenetics and ecological niche models (ENM) to examine whether congeneric species of Callogorgia (Octocorallia: Primnoidae) occupy different ecological niches across the continental slope of the Gulf of Mexico (GoM) and whether this niche divergence could be important in the evolution of these closely related species. Callogorgia americana americana, Callogorgia americana delta and Callogorgia gracilis were documented at 13 sites in the GoM (250–1000 m) from specimen collections and extensive video observations. On a first order, these species were separated by depth, with C. gracilis occurring at the shallowest sites, C. a. americana at mid‐depths and C. a. delta at the deepest sites. Callogorgia a. delta was associated with areas of increased seep activity, whereas C. gracilis and C. a. americana were associated with narrow, yet warmer, temperature ranges and did not occur near cold seeps. ENM background and identity tests revealed little to no overlap in ecological niches between species. Temporal calibration of the phylogeny revealed the formation of the Isthmus of Panama was a vicariance event that may explain some of the patterns of speciation within this genus. These results elucidate the potential mechanisms for speciation in the deep sea, emphasizing both bathymetric speciation and vicariance events in the evolution of a genus across multiple regions.     

Complement-mediated unspecific binding of immunoglobulins to some endocrine cells

Summary Unspecific binding of immunoglobulins to gastrin G cells, glucagon A cells and somatostatin D cells of the gastric mucosa or pancreas, as well as to the calcitonin-somatostatin cells of rabbit thyroid has been found to occur through a non antigen-antibody mechanism mediated at least in part by the C_1q fraction of complement. The phenomenon represents a major drawback in hormone immunohistochemistry, which can be prevented by incubating the specific anti-hormone sera with anti-C_1q antibodies or with complement-fixing immunocomplexes.     

A BASIC microcomputer program for prediction of B and T cell epitopes in proteins

A BASIC microcomputer program (EPIPLOT) has been developed forpredicting B and T cell antigenic sites in proteins from theirprimary structures. The program calculates and plots flexibility,hydrophilicity and antigenicity profiles using 13 differentscales, chosen as those yielding the best predictions on proteinswhose antigenic structures are known. T cell epitope predictionis basedon published algorithms focused on amphiphilic structuresand characteristic sequence patterns. The advantages of jointpredictions in locating T cell antigenic sites are also discussed. Received on December 12, 1989; accepted on January 31, 1990     

Assessment of cetacean–fishery interactions in the marine food web of the Gulf of Taranto (Northern Ionian Sea,Central Mediterranean Sea)

Reviews in Fish Biology and Fisheries - The exploitation of fishery resources acts as a driving force on cetaceans both directly, by determining their fishing mortality or injury as by-catch...     

An older origin for the Acheulean at Melka Kunture (Upper Awash,Ethiopia): Techno-economic behaviours at Garba IVD

In the 1970s and 1980s, the emergence of the Acheulean at Melka Kunture (Upper Awash, Ethiopia) was dated to 1 Ma (million years ago), based on the typo-metrical analysis of the lithic assemblage of Garba XIIJ. Older sites such as Gombore I, Karre I, and Garba IV (1.7–1.5 Ma) were classified as Oldowan/Developed Oldowan. Consequently, the Oldowan and the Acheulean at Melka Kunture were interpreted as two distinct technologies separated by a chronological gap of 0.5 Ma.     

Effects of habitat conditions at hatching time on growth history of offspring European anchovy, <Emphasis Type="Italic">Engraulis encrasicolus</Emphasis>, in the Central Mediterranean Sea

Species distributions are structured by regional and local determinants, which operate at multiple spatial and temporal scales. The purpose of our work was to distinguish the relative roles of local variables, climate, geographical location and post glaciation condition (i.e., delineation between supra- and subaquatic lakes during the post-glacial Ancylus Lake) in explaining variation in macrophyte community composition of all taxa, helophytes and hydrophytes. In addition, we investigated how these four explanatory variable groups affected macrophyte strategy groups based on Grime’s classification. Using partial linear regression and variation partitioning, we found that macrophyte communities are primarily filtered by local determinants together with regional characteristics at the studied spatial scale. We further evidenced that post glaciation condition indirectly influenced on local water quality variables, which in turn directly contributed to the macrophyte communities. We thus suggest that regional determinants interact with local-scale abiotic factors in explaining macrophyte community patterns and examining only regional or local factors is not sufficient for understanding how aquatic macrophyte communities are structured locally and regionally.     

Pyrrolooxygenases: A new type of oxidases

Summary A new type of oxygenases was isolated from plant and animal sources which oxidized pyrrole and indole derivatives. They had a broad substrate specificity and were called pyrrolooxygenases. Three different enzymes within the group were identified; skatole pyrrolooxygenase, tryptophan pyrrolooxygenase and porphobilinogen oxygenase. The first two oxidized the pyrrole ring of the various indole derivatives affording substituted o-formanidophenacyl derivatives as the main oxidation products. Tryptophan pyrrolooxygenase also oxidized the tryptophanyl residues of peptides and enzymes. When those residues were essential for the activity of the tryptophan containing enzymes, then inactive enzymes were obtained.Porphobilinogen oxygenase oxidized porphobilinogen and related alkylpyrrole compounds affording 3-pyrrolin-2-one derivatives. The pyrrolooxygenases acted as mixed-function oxidases, since they required the presence of oxygen and of a reducing agent. The substrate, the oxygen and the reductant were consumed in equimolar amounts. The best artificial reducing agent was sodium dithionite. Illuminated active chloroplasts were the natural reducing agent of the plant enzymes and NADPH was the reducing agent of the animal enzymes. Pyrrolooxygenases were located in the chloroplasts of green leaves and in the microsomes in the case of the mammalian enzymes. The activity of the enzymes in the crude extracts was usually low, due to the presence in the same of a protein inhibitor. When the inhibitor was separated by protein fractionation methods, full enzymatic activity was recovered. Destruction of the inhibitor by aging or by temperature had the same effect. The very low oxygenase activity present in the microsomal rat liver preparations could be strongly enhanced by previous administration to the rats of phenobarbital or steroids. This induction of the oxygenase activity was coincident with a drop in the amount of inhibitor present in the extracts.The properties and metabolic role of the pyrrolooxygenases are discussed.