Evolutionary conservation of the chromosomal configuration and regulation of amylase genes among eight species of the Drosophila melanogaster species subgroup

Nuclear DNA was extracted from each of the eight species comprising the Drosophila melanogaster species subgroup. Southern hybridization of this DNA by using a molecular probe specific for the alpha-amylase coding region showed that the duplicated structure of the amylase locus, first found in D. melanogaster, is conserved among all species of the melanogaster subgroup. Evidence is also presented for the concerted evolution of the duplicated genes within each species. In addition, it is shown that the glucose repression of amylase gene expression, which has been extensively studied in D. melanogaster, is not confined to this species but occurs in all eight members of the species subgroup. Thus, both the duplicated gene structure and the glucose repression of Drosophila amylase gene activity are stable over extended periods of evolutionary time.      

The use of picolinyl esters for the characterization of microbial lipids: application to the unsaturated and cyclopropane fatty acids of campylobacter species

Picolinyl esters have been recently introduced for the mass spectrometric structure determination of unsaturated and cyclopropane fatty acids. We have used these derivatives to characterize the unsaturated and cyclopropane acids of Campylobacter species . The principle unsaturated acids were shown to be 11-octadecenoic acid, with smaller amounts of 9-hexadecenoic acid, 9-octadecenoic acid and 9, 11-octadecadienoic acid. The only cyclopropane acid present was cis 11, 12-methylene octadecanoic acid. There was no interspecific variation in the position of unsatu-ration or methylene bridges, even in the recently discovered gastric Campylobacter like organisms (GCLO) or the urease positive thermophilic Campylobacters (UPTC), the fatty acid profiles of which were consistent with their inclusion in the genus Campylobacter .     

Growth of Phytomonas serpens in a Defined Medium; Nutritional Requirements

ABSTRACT. Three strains of Phytomonas serpens two from tomatoes, Lycopersicon esculentum one from the insect Phtia picta (Hemiptera, Coreidae), were cultivated in a chemically defined medium developed from a defined medium for cultivating insect flagellates. Besides organic growth factors required by other insect trypanosomatids this flagellate requires, serine and inositol. Glutamine stimulates growth, and, surprisingly, does not require heme.     

Membrane Skeletal Proteins and Their Integral Membrane Protein Anchors are Targets for Tyrosine and Threonine Kinases in Euglena

ABSTRACT. Proteins of the membrane skeleton of Euglena gracilis were extensively phosphorylated in vivo and in vitro after incubation with [³²P]-orthophosphate or γ-[³²P] ATP. Endogenous protein threonine/serine activity phosphorylated the major membrane skeletal proteins (articulins) and the putative integral membrane protein (IP39) anchor for articulins. The latter was also the major target for endogenous protein tyrosine kinase activity. A cytoplasmic domain of IP39 was specifically phosphorylated, and removal of this domain with papain eliminated the radiolabeled phosphoamino acids and eliminated or radically shifted the PI of the multiple isoforms of IP39. In gel kinase assays IP39 autophosphorylated and a 25 kDa protein which does not autophosphorylate was identified as a threonine/serine (casein) kinase. Plasma membranes from the membrane skeletal protein complex contained threonine/serine (casein) kinase activity, and cross-linking experiments suggested that IP39 was the likely source for this membrane activity. pH optima, cation requirements and heparin sensitivity of the detergent solubilized membrane activity were determined. Together these results suggest that protein kinases may be important modulators of protein assembly and function of the membrane skeleton of these protistan cells.     

Sequence variation in the outer-surface-protein genes of Borrelia burgdorferi

Borrelia burgdorferi is a spirochete pathogen transmitted among warm- blooded hosts by ixodid ticks. Frequency-dependent selection for variant outer-surface proteins might be expected to arise in this species, since rare variants are more likely to avoid immune surveillance in previously infected hosts. We sequenced the OspA and OspB genes of nine North American strains and compared them with nine strains previously described. For each gene, the mean number of synonymous substitutions per synonymous site and the mean number of nonsynonymous substitutions per nonsynonymous site show only a twofold excess of silent mutations. Synonymous rates vary widely along the OspB protein. Some regions show a significant excess of silent substitutions, while divergence in other regions is constrained by biased base composition or selection. The presence, in antigenically important regions of the protein, of significant variation among strains, as well as evidence for recombination among strains, should be considered in attempts to develop vaccines against this disease.      

Characterisation of a 34 kD protein from potato cyst nematodes, using monoclonal antibodies with potential for species diagnosis

Two monoclonal antibodies, which differentially recognise the two species of potato cyst nematodes (PCN), Globodera pallida and G. rostochiensis, are described. They have been shown to have potential for quantification of these two species, recognising proteins of the same molecular weight (34 kD) in both species. Further investigation showed these proteins to have isoelectric points at pH values of 5.7 in G. pallida and 5.9 in G. rostochiensis, in common with the proteins used by Fleming & Marks (1983) to differentiate the species of PCN. They are likely to be structurally very similar, with the same physiological function (and therefore similar concentrations) in the two species. In cross-reactivity tests with a wide range of soil nematode species, the antibodies reacted strongly only with species of the genus Globodera, and thereby confirmed their potential as the basis of a quantitative immunoassay likely to be useful in management of PCN populations.     

Characterization of novel long-chain 1,2-diols in Thermus species and demonstration that Thermus strains contain both glycerol-linked and diol-linked glycolipids.

In this study, we purified and characterized tetra- and triglycosyl glycolipids (GL-1 and GL-2, respectively) from two different colonial forms of Thermus scotoductus X-1, from T. filiformis Tok4 A2, and from T. oshimai SPS-11. Acid hydrolysis of the purified glycolipids liberated, in addition to the expected long-chain fatty acids, two components which were identified by gas chromatography-mass spectrometry as 16-methylheptadecane-1,2-diol and 15-methylheptadecane-1,2-diol. Fast atom bombardment mass spectrometry of the intact glycolipids indicated that a major proportion consisted of components with glycan head groups linked to long-chain 1,2-diols rather than to glycerol, although in all cases glycerol-linked compounds containing similar glycan head groups were also present. As in other Thermus strains, the polar head group of GL-1 from T. filiformis Tok4 A2 and from T. scotoductus X-1 colony type t2 was a glucosylgalactosyl-(N-acyl)glucosaminylglucosyl moiety. However, GL-2 from T. scotoductus X-1 colony type t1 and from T. oshimai SPS-11 was a truncated analog which lacked the nonreducing terminal glucose. Long-chain 1,2-diols have been previously reported in the polar lipids of Thermomicrobium roseum and (possibly) Chloroflexus aurantiacus, but to our knowledge, this is the first report of their detection in other bacteria and the first account of the structural determination of long-chain diol-linked glycolipids.     

Patterns of shortening and thickening of the human diaphragm

Wait, J. L., and R. L. Johnson. Patterns of shorteningand thickening of the human diaphragm. J. Appl.Physiol. 83(4): 1123-1132, 1997.To study how the human diaphragm changesconfiguration during inspiration, we simultaneously measured diaphragmthickening using ultrasound and inspired volumes using apneumotachograph. Diaphragm length was assessed by chest radiography.We found that thickening and shortening were greatest during a breathtaken primarily with the abdomen. However, the degree of thickening wasgreater than expected for fiber shortening, assuming parallel musclefibers and no shear. So, to clarify this unexpected finding, weconsidered geometric models of the diaphragm. How a muscle thickens asits fibers shorten is critically dependent on geometry. Thus, if a flatrectangular sheet of muscle shortens along one dimension, surfacearea-to-length ratio along this dimension should remain constant, andthickness would be inversely proportional to length during shortening.The simplest model of the diaphragm, however, is a cylindrical sheet ofmuscle in the zone of apposition capped by a dome; the ratio of surfacearea to radial fiber length in the dome is substantially less than theratio of area to length of the cylindrical zone of apposition; hence,as the zone of apposition shortens while the dome radius remainsconstant, the ratio of total surface area to combined length (i.e.,dome + zone of apposition) must decrease and thickening of the musclecorrespondingly must increase more than expected for a simplerectangular strip. A similar relationship can be derived betweenthickening and length in a muscle sheet with a wedge-shaped insertioninto a thin flat tendon. Comparison of calculations with these types ofmodels to data from human subjects indicates that the unexpectedthickening in the zone of apposition is explained by the peculiargeometry of the diaphragm. The greater thickening of the diaphragm inthe zone of apposition suggests that more of the muscle mass and more sarcomeres are retained in the zone of apposition as the dome descends.Physiologically, this greater thickening may have importance byreducing wall stress in the zone of apposition and reducing the work orenergy requirements per sarcomere.