A highly conserved nuclear gene for low-level phylogenetics: elongation factor-1 alpha recovers morphology-based tree for heliothine moths

Molecular systematists need increased access to nuclear genes. Highly conserved, low copy number protein-encoding nuclear genes have attractive features for phylogenetic inference but have heretofore been applied mostly to very ancient divergences. By virtue of their synonymous substitutions, such genes should contain a wealth of information about lower-level taxonomic relationships as well, with the advantage that amino acid conservatism makes both alignment and primer definition straightforward. We tested this postulate for the elongation factor-1 alpha (EF-1 alpha) gene in the noctuid moth subfamily Heliothinae, which has probably diversified since the middle Tertiary. We sequenced 1,240 bp in 18 taxa representing heliothine groupings strongly supported by previous morphological and allozyme studies. The single most parsimonious gene tree and the neighbor-joining tree for all nucleotides show almost complete concordance with the morphological tree. Homoplasy and pairwise divergence levels are low, transition/transversion ratios are high, and phylogenetic information is spread evenly across gene regions. The EF-1 alpha gene and presumably other highly conserved genes hold much promise for phylogenetics of Tertiary age eukaryote groups.      

Mesodern-inducing factors and mesodermal patterning

Identification of the signalling molecules involved in mesoderm formation in amphibian embryos still presents problems. None of the original candidates, such as activin, have been definitively ruled out, and the new factors, such as the nodal-related genes, have come on to the scene. Of the original candidates, activin has been definitively shown to act as a morphogen, whereas bone morphogenetic protein (BMP)-4 has emerged as a ventral inducer and an inhibitor of neural differentiation. The effects of BMP-4 are antagonized by chordin, a molecule related to the product of the Drosophila gene short gastrulation.     

Isolation of plasma membrane glycoprotein from bovine thymocytes

Glycoprotein was isolated from a purified thymocyte membrane preparation by two methods: lithium diiodosalicylate-phenol extraction and hot 75% ethanol extraction. A higher yield of membrane sialic acid was obtained by the latter method. The preparations had similar apparent molecular weights on sodium dodecyl sulfate gel electrophoresis. Both had similar receptor activities against a panel of hemagglutinins, although the 75% ethanol extract was more active on a weight basis. However, there were significant differences in carbohydrate and amino acid compositions of the two thymocyte extracts. The lithium diiodosalicylate-extracted material had much more glucose, ribose, and glycine than the ethanol extract. The glycoprotein preparations from thymocytes were quite distinct from the glycoprotein of bovine erythrocytes in both composition and receptor properties.     

Disturbance and predation in an assemblage of herbivorous Diptera and algae on rocky shores

Summary Speculation about the effects of disturbance in marine benthic communities is often based on competition theory. Disturbances are thought to provision numerically depleted or competitively inferior species with resources associated with open substrate. However, disturbances that remove entire assemblages of sessile species also alter trophic structure, and thereby, influence the outcome of predator/prey relations. Aspects of community structure may be determined by patterns of disturbance and predation.The influence of disturbance and predation on the distribution and seasonality of blooms of ephemeral algae and associated Diptera was investigated with field experiments at several rocky beaches in central California. Blooms of ephemeral algae developed on high intertidal rock faces that were subject to severe seasonal disturbances caused by shifting sediment. These were subsequently colonized by the herbivorous larvae of several Diptera species for predictable periods each year. Other areas, without blooms, were not so disturbed.Experiments were done to determine if seasonal blooms were caused by seasonal disturbances that remove predators which otherwise might prevent the establishment of the Diptera/algae assemblage. The predators were crabs and limpets which eat both algae and larvae while foraging. Blooms of algae and larvae did not develop when limpets were transplanted to disturbed areas in periods between disturbances. Adjacent control areas did support blooms. Transplanted limpets did not survive periods of burial. When both limpets and crabs were excluded from treatment plots in undisturbed areas, blooms developed where they would not otherwise have occurred; controls remaied unchanged. Crabs and limpets differed in their effects on this assemblage. Crabs recruited quickly to the site of a bloom, but did not crop algal cover as closely, nor decrease larval density as much as the slowly recruiting limpets.The results suggest that disturbances favor blooms of some species by reducing predation. Severe localized disturbances increased the variability of the upper shore community by creating a patchwork of differing predator/prey abundances.     

Dynamic properties of cat tenuissimus muscle

Some of the factors which influence the development of tension in cat tenuissimus muscle were studied quantitatively. Under isometric conditions, it was shown that the dynamic properties of the relationship between the tension of the muscle and its electrical stimulation depend on the mean rate of stimulation. This non-linear effect cannot be explained on the basis of the dependence of muscle tension on instantaneous rate of stimulation since the tension due to a stimulus following closely a previous stimulus is augmented, but the time course of the twitch response is unaltered. The interaction between the tension due to active contraction and that due to the viscoelastic properties of the muscle was investigated by independently varying muscle length and the rate of stimulation. Within the limits of resolution of the data, it was concluded that these two components of tension are additive and that muscle stiffness is related to the instantaneous tension of the muscle.     

Optimization of the enzymatic synthesis of structured triacylglycerols rich in docosahexaenoic acid at sn-2 position by acidolysis of Aurantiochytrium limacinum SR21 oil and caprylic acid using response surface methodology

Journal of Applied Phycology - The thraustochytrid Aurantiochytrium limacinum SR21 is a promising source of docosahexaenoic acid (DHA) for human consumption as dietary supplement, replacing...     

Phosphitylation of Primary Carboxamides. Synthesis of Peptide-Oligonucleotide Conjugates with Acylphosphoramidate Linkages

Abstract

N-acylphosphoramidates can be obtained from the reaction of phosphitylated primary carboxamides and an alcohol in the presence of an acid catalyst such as tetrazole and subsequent oxidation. The reaction is useful for the preparation of peptide-oligonucleotide conjugates.