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.      

Chick embryo fibroblasts produce two forms of hyaluronidase

Cultured chick embryo fibroblasts derived from skin and skeletal muscle exhibit hyaluronidase activity both associated with the cell layer and secreted into the medium. Although both forms of the enzyme have a number of similar characteristics (R.W. Orkin and B.P. Toole, 1980, J. Biol. CHem. 255), they differ in thermal stability at neutral pH and in behavior on ion-exchange chromatography. Both forms of the enzyme are equally stable at acidic pH for long intervals, but the cell-associated hyaluronidase is significantly less stable than the secreted froms at neutral pH and at temperatures more than or equal to 30 degrees C. Neither the presence of proteases nor inhibitors of hyaluronidase appear to be involved in the cell-asspcoated enzyme. Chromatography of the two forms of hyaluronidase on carboxymethyl cellulose reveals that most (60-90 percent) of the secreted form of the enzyme elutes at a lower ionic strength than the cell- associated enzyme. Treatment of the secreted form of hyaluronidase with neuraminidase shifts its elution profile on carboxymethyl cellulose toward that of the cell-associated form, and also decreases its thermal stability at neutral pH. In contrast, treatment of the secreted form of hyaluronidase with alkaline phosphatase has no detectable effect. These data suggest that the secreted hyaluronidase differs from the cellular form in possessing additional sialic acid residues which endow the former with increased stability in the extracellular milieu.     

Immunolocalization of multiple Galpha subunits in mammalian spermatozoa and additional evidence for Galphas

Like somatic cells, mammalian spermatozoa appear to contain several different heterotrimeric G protein alpha-subunits that could mediate specialized cell responses. However, the precise Galpha subunits present, their subcellular location and their possible roles are still incompletely defined. In this study, using commercially available specific antibodies, we have shown by immunoblotting that Galpha(s) is present in human and mouse sperm lysates. Immunolocalization using intact spermatozoa from both species revealed this protein to be in the acrosomal cap region and the flagellum, particularly the principal piece. Treatment of permeabilized mouse spermatozoa with cholera toxin led to enhanced ADP-ribosylation of a protein the same size as Galpha(s), as well as an increase in cAMP, providing further proof for Galpha(s). Evidence for the presence and distinct localizations of Galpha(i2), Galpha(i3), Galpha(o), Galpha(q/11), and Galpha(olf) was also obtained. Of particular interest was Galpha(i2) which, like Galpha(s), was present in the acrosomal cap region and flagellum, the same regions where stimulatory and inhibitory adenosine receptors are localized. These observations are consistent with our hypothesis that G proteins mediate adenosine receptor modulation of adenylyl cyclase, with consequent alterations in cAMP production, apparently crucial for the spermatozoon's acquisition and maintenance of fertilizing ability.     

Chinch bug-resistant buffalograss: an investigation of tolerance, antixenosis, and antibiosis

Choice and no-choice studies were conducted to determine the categories (antibiosis, antixenosis, and tolerance) of resistance of four buffalograsses (NE91-118, 'Bonnie Brae', 'Cody', and 'Tatanka') previously identified as resistant to the western chinch bug, Blissus occiduus Barber. Antibiosis studies found no significant differences in western chinch bug fecundity, nymphal development, or survival among the resistant and susceptible buffalograsses. Tolerance studies indicated that NE91-118, Cody, and Tatanka exhibited moderate-to-high levels of tolerance based on western chinch bug damage ratings and plant height, whereas Bonnie Brae exhibited moderate-to-low levels of tolerance. Choice studies indicated the presence of antixenosis in NE91-118, whereas Cody and Tatanka showed little or no antixenosis. Scanning electron microscopy was used to disclose morphological differences between NE91-118 (resistant) and '378' (susceptible). The epicuticular wax structures and trichome densities were similar between 378 and NE91-118, suggesting that morphological structures do not contribute to NE91-118 antixenosis.     

Buffalograss germplasm resistance to Blissus occiduus (Hemiptera: Lygaeidae)

Plant germplasm collections may offer genetic variability useful in identifying insect resistance. The goal of this project was to evaluate buffalograss genotypes [Buchlo? dactyloides (Nutt.) Engelm.] for resistance to the chinch bug, Blissus occiduus Barber (Hemiptera: Lygaeidae), and to relate resistance to ploidy level, chinch bug number, and pubescence. Forty-eight buffalograss genotypes from diverse geographic locations were evaluated in replicated studies under greenhouse conditions. Of the genotypes studied, four were highly resistant, 22 were moderately resistant, 19 were moderately susceptible, and three were highly susceptible to chinch bug damage. The mean number of chinch bugs was significantly different among the 48 genotypes. There was no significant correlation between chinch bug resistance and ploidy level or chinch bug resistance and pubescence. These results indicate the genetic source of resistance to chinch bugs exists in buffalograss germplasm. Highly resistant genotypes can be used in breeding programs to further improve buffalograss cultivars.     

Turfgrass, crop, and weed hosts of Blissus occiduus (Hemiptera: Lygaeidae)

Blissus occiduus Barber is an important pest of buffalograss, Buchlo? dactyloides (Nuttall) Engelmann, turf. No-choice studies documented the susceptibility of selected turfgrasses, crops, and weeds to B. occiduus feeding. Highly to moderately susceptible grasses included buffalograss; yellow Setaria glauca (L.) and green foxtail Setaria viridis (L.); Kentucky bluegrass, Poa pratensis L.; perennial ryegrass, Lolium perenne L.; brome, Bromus spp. Leyss.; zoysiagrass, Zoysia japonica Steudel; Bermuda grass, Cynodon dactylon (L.) Pers.; sorghum, Sorghum bicolor (L.) Moench; tall fescue, Festuca arundinacea Schreb.; and barley Hordeum vulgare (L.). Slightly to nonsusceptible grasses included fine fescue, Festuca ovina hirtula L.; rye, Secale cereale L.; crabgrass Digitaria sanguinalis (L.); bentgrass, Agrostis palustris Huds.; wheat, Tritium aestivun L.; corn, Zea mays L.; fall panicum Panicum dichotomiflorum Michx.; and St. Augustinegrass, Stenotaphrum secundatum (Walt.) Kuntze. The reproductive potential of B. occiduus was also investigated on these same grasses. B. occiduus produced offspring on 15 of the 18 turfgrass, crop, and weed species evaluated. No reproduction occurred on either Bermuda grass or St. Augustinegrass, and buffalograss plants were killed by B. occiduus feeding before offspring could be produced.     

Nepetalactones from essential oil of Nepeta cataria represent a stable fly feeding and oviposition repellent

The stable fly, Stomoxys calcitrans (L.) (Diptera: Muscidae), is one of the most serious pests to livestock. It feeds mainly on cattle and causes significant economic losses in the cattle industry. Standard stable fly control involving insecticides and sanitation is usually costly and often has limited effectiveness. As we continue to evaluate and develop safer fly control strategies, the present study reports on the effectiveness of catnip (Nepeta cataria L.) oil and its constituent compounds, nepetalactones, as stable fly repellents. The essential oil of catnip reduced the feeding of stable flies by >96% in an in vitro bioassay system, compared with other sesquiterpene-rich plant oils (e.g. amyris and sandalwood). Catnip oil demonstrated strong repellency against stable flies relative to other chemicals for repelling biting insects, including isolongifolenone, 2-methylpiperidinyl-3-cyclohexen-1-carboxamide and (1S,2'S)-2-methylpiperidinyl-3-cyclohexen-1-carboxamide. The repellency against stable flies of the most commonly used mosquito repellent, DEET, was relatively low. In field trials, two formulations of catnip oil provided >95% protection and were effective for up to 6 h when tested on cattle. Catnip oil also acted as a strong oviposition repellent and reduced gravid stable fly oviposition by 98%.     

Structural and Functional Integration of the PLCγ Interaction Domains Critical for Regulatory Mechanisms and Signaling Deregulation

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Highlights? Domains from PLCγ regulatory region show structural and functional integration ? Only cSH2 domain interacts with the PLC-core forming a high affinity surface ? Activation involves removal of autoinhibition and dissociation from the receptor ? Disease-linked mutations map to the autoinhibitory interface