Camouflage patterns in Nautilus, and their implications for cephalopod paleobiology

Cowen, R., Gertman, R. & Wiggett, Gail: Camouflage patterns in Nautilus , and their implications for cephalopod paleobiology.
Formal analysis of the pigment patterns of adult Nautilus shows that they are perfectly camouflaged for life in open water. But because of their accretionary growth pattern, juveniles are not fully camouflaged for open water: this supports previous suggestions that young Nautilus are benthonic. The principles of camouflage are used to re-assess some facets of cephalopod paleobiology. The life orientation of some early cyrtocones is re-interpreted. 'Ornament' on ammonoids is seen as camouflage structure, and we infer photic-nektonic, photic-benthonic, and aphotic habitats for three major morphological groups of ammonites. Sexual dimorphism in ammonites was probably accompanied by sexual separation in habitat, except for a short (annual) mating season. This is not inconsistent with modern cephalopod biology.     

Life-cycles of lotic populations of Spongilla lacustris and Eunapius fragilis (Porifera: Spongillidae)

SUMMARY. The life-cycles of green and white morphs of the freshwater sponge Spongilla lacustris were examined in the light of past evidence that zoochlorellae may augment their sponge host's nutrition. Field collections from a lotic population of S. lacustris were supplemented by laboratory experiments on gemmule hatching and gemmule size. Both white and green S. lacustris produced sperm for a 6-week period in 1976 starting in the middle of May. Out of thirty white and thirty green sponges examined during this period, twenty white and ten green sponges contained sperm. Sperm production in both morphs was limited primarily to the basal 3.18mm of sponge tissue, and the density of sperm packets in the two morphs was the same. Out of 180 white and green sponges examined in 1976, only four eggs, no embryos, and no larvae were observed. White sponges gemmulated a week or two earlier, and produced smaller gemmules which were more uniform in size than those of green sponges. White and green gemmules hatched synchronously in the spring. In 1977 one female and numerous male specimens of S. lacustris , and numerous females but no males of another sponge, Eunapius fragilis , were found. The life-cycles are discussed in the light of other recent studies on freshwater sponges.     

Pseudomonas syringae pv. syringae B728a hydrolyses indole-3-acetonitrile to the plant hormone indole-3-acetic acid

Nitrilase enzymes catalyse the hydrolysis of nitrile compounds to the corresponding carboxylic acid and ammonia, and have been identified in plants, bacteria and fungi. There is mounting evidence to support a role for nitrilases in plant–microbe interactions, but the activity of these enzymes in plant pathogenic bacteria remains unexplored. The genomes of the plant pathogenic bacteria Pseudomonas syringae pv. syringae B728a and Pseudomonas syringae pv. tomato DC3000 contain nitrilase genes with high similarity to characterized bacterial arylacetonitrilases. In this study, we show that the nitrilase of P. syringae pv. syringae B728a is an arylacetonitrilase, which is capable of hydrolysing indole-3-acetonitrile to the plant hormone indole-3-acetic acid, and allows P. syringae pv. syringae B728a to use indole-3-acetonitrile as a nitrogen source. This enzyme may represent an additional mechanism for indole-3-acetic acid biosynthesis by P. syringae pv. syringae B728a, or may be used to degrade and assimilate aldoximes and nitriles produced during plant secondary metabolism. Nitrilase activity was not detected in P. syringae pv. tomato DC3000, despite the presence of a homologous nitrilase gene. This raises the interesting question of why nitrilase activity has been retained in P. syringae pv. syringae B728a and not in P. syringae pv. tomato DC3000.     

Woody biomass production during the second rotation of a bio-energy Populus plantation increases in a future high CO2 world

The quickly rising atmospheric carbon dioxide (CO₂)‐levels, justify the need to explore all carbon (C) sequestration possibilities that might mitigate the current CO₂ increase. Here, we report the likely impact of future increases in atmospheric CO₂ on woody biomass production of three poplar species (Populus alba L. clone 2AS‐11, Populus nigra L. clone Jean Pourtet and Populus×euramericana clone I‐214). Trees were growing in a high‐density coppice plantation during the second rotation (i.e., regrowth after coppice; 2002–2004; POPFACE/EUROFACE). Six plots were studied, half of which were continuously fumigated with CO₂ (FACE; free air carbon dioxide enrichment of 550 ppm). Half of each plot was fertilized to study the interaction between CO₂ and nutrient fertilization. At the end of the second rotation, selective above‐ and belowground harvests were performed to estimate the productivity of this bio‐energy plantation. Fertilization did not affect growth of the poplar trees, which was likely because of the high rates of fertilization during the previous agricultural land use. In contrast, elevated CO₂ enhanced biomass production by up to 29%, and this stimulation did not differ between above‐ and belowground parts. The increased initial stump size resulting from elevated CO₂ during the first rotation (1999–2001) could not solely explain the observed final biomass increase. The larger leaf area index after canopy closure and the absence of any major photosynthetic acclimation after 6 years of fumigation caused the sustained CO₂‐induced biomass increase after coppice. These results suggest that, under future CO₂ concentrations, managed poplar coppice systems may exhibit higher potential for C sequestration and, thus, help mitigate climate change when used as a source of C‐neutral energy.     

Evolution of water surface locomotion by spiders: a comparative approach

Spiders vary enormously in their behaviour when placed on the surface of fresh water. In some families (e.g. Theridiidae), the spider typically becomes wet and either sinks or is incapacitated by adhesion to the water. In other families (e.g. Agelenidae), the spider remains dry and moves across the water using its legs in much the same way it does on land, with the members of each leg pair moving in alternation with each other. In at least one family (Pisauridae), the spider remains dry and moves across the water using a rowing or galloping gait in which the members of each propulsive pair of legs move in synchrony with each other. While some degree of hydrophobicity is widespread among spiders, the ability to move on water by rowing occurs rarely; it is common only among families in the Lycosoidea, which is a subset of the GST (Grate-Shaped Tapetum) clade. Our mapping of water surface locomotion behaviour of representatives of 42 families of spiders onto cladograms of the Araneae suggests that the ability to row evolved at the base of the clade that includes Trechaleidae, Pisauridae and Lycosidae and evolved independently in some members of the family Ctenidae. Rowing behaviour is seen in all subfamilies of Lycosidae but, unlike in the Pisauridae in which all animals tested showed the rowing behaviour, many individuals that could row did not do so all of the time. Among the 166 non-lycosoid species we have tested, we have found one species of Araneidae and two species of Salticidae that can row. It is evident from our data that, in most spiders, phylogeny trumps recent selection (based on habitat preference) in determining the spiders' locomotor behaviour on the water surface.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 81 , 63–78.     

ABILITY OF HAND EVALUATION VERSUS MOUTH EVALUATION TO DIFFERENTIATE TEXTURE OF CHEESE

Hand evaluation and mouth evaluation were compared for texture of cheese. Panelists (n = 11) identified seven mouth terms and five hand terms and developed definitions and standard procedures for evaluation during the course of training. The terms were used to evaluate texture properties of fourteen different types of natural and processed full fat and reduced fat cheeses. Hand and mouth evaluation were able to discriminate cheese texture (P≦0.05). Principal component analysis of data revealed that hand and mouth evaluation differentiated the cheeses in a similar manner. Correlation analysis, factor analysis, and canonical analysis revealed that mouth and hand terms were highly correlated (P≦0.05). Either hand or mouth evaluation can be used to discriminate cheese texture.     

Fission in Heteropolar Tandem Grafts of the Ciliate Stentor coeruleus*

SYNOPSIS Stentor pairs fused by their posterior ends show persisting mutual adhesion, tho they eventually pull apart. When immobilized in methyl cellulose these grafts constricted in 2 in the line of heal. In no other type of stentor graft has such deliberate separation been observed.     

Somatic chromosome number doubling of selected potato genotypes using callus culture or the colchicine treatment of shoot nodes in vitro

Experiments were carried out to double the somatic cell chromosome numbers of a monoploid and dihaploid of Solanum tuberosum and a genotype of S. circaeifolium subsp. quimense. Colchicine was used in vitro on shoot nodes from which the axillary meristems had been removed. Plants with doubled chromosome numbers were obtained from shoots grown from the tertiary, sub-axillary meristems of all three genotypes. The callus culture of stem and leaf explants was found to produce more shoots with doubled chromosome numbers than the colchicine treatment in the case of the dihaploid and quimense genotypes but no shoots were obtained from callus culture of the monoploid. Fifty-two % of the shoots from the dihaploid and 63% from the quimense clone were ploidy doubled in the case of the best callus culture system. Using a sub-lethal dose of colchicine, the dihaploid yielded 37% ploidy-doubled shoots whereas all the shoots produced from the monoploid were doubled and the quimense clone produced 27% doubled plants. Callus culture was highly dependent upon the type of growth medium and other, unknown, factors. The colchicine treatment, although yielding fewer products, was more reliable for achieving ploidy doubling in selected clones if the number of plants produced is not important.