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T P Freeman

Publications and source records attributed to T P Freeman.

13 recordsLinked to original sources
PubMed2003

Cuticular lipids and silverleaf whitefly stage affect conidial germination of Beauveria bassiana and Paecilomyces fumosoroseus.

Beauveria bassiana and Paecilomyces fumosoroseus are generalist entomopathogenic fungi that infect the silverleaf whitefly (Bemisia argentifolii). We found second and third instar whiteflies to be the most susceptible larval stage to both fungi. Conidia of B. bassiana germinated most readily on the cuticle of second instars (54% germinated) and P. fumosoroseus germination was highest on third instar cuticle (45%). Fourth instars (the ultimate instar) had low susceptibility to these pathogens, and spore germination on the cuticle of fourth instars was very low for B. bassiana (7%) and intermediate for P. fumosoroseus (33%). Cuticular lipids were found to have toxic or inhibitory effects on conidia of B. bassiana and P. fumosoroseus when the spores were germinated on nutrient agar in the presence of the lipids. In the absence of added nutrients, P. fumosoroseus conidial germination increased in the presence of the lipids. To test if the inhibitory effects of the lipids were due solely to hydrophobicity (preventing water from coming into contact with the conidia) we tested the effects of synthetic long-chain wax esters. The synthetic wax esters inhibited germination of P. fumosoroseus to a degree that was similar to the effect of the cuticular lipid extracts, but the synthetic lipids did not have a significant effect on B. bassiana. Thus, the thick coating of long-chain wax esters produced by whitefly nymphs affect spore germination of fungal pathogens, but whether they play a significant role in defense against disease is not clear.

Animals↗
PubMed2000

Cryopreservation of Musca domestica (Diptera: Muscidae) embryos.

Prior studies on cryopreserving embryos of several non-drosophilid flies established that two Drosophila melanogaster embryo cryopreservation protocols were not directly suitable for use with these species. This paper describes our work on developing a protocol for cryopreservation of embryos of the housefly, Musca domestica. Significant progress was made when permeabilization of the vitelline membrane was optimized, a vitrification solution containing ethylene glycol, polyethylene glycol, and trehalose was formulated, and when cooling and recovery of the cryopreservation protocol included a step which passed the embryos through liquid nitrogen vapor. More than 70% of housefly embryos withstand treatments of dechorionation, permeabilization, loading with cryoprotectant, and dehydration in vitrification solution, but the cooling, warming, and poststorage rearing steps still cause a considerable reduction in survival. About 53% of the vitrified M. domestica embryos hatched into larvae. Relative to the percentage of the control adult emergence, about 13% of the embryos stored in liquid nitrogen developed into fertile adults. Hatching of the F(1) progeny of adults having been cryopreserved as embryos was similar to control levels.

2-Propanol↗
PubMed2000

Waxes and lipids associated with the external waxy structures of nymphs and pupae of the giant whitefly, Aleurodicus dugesii.

The nymphs and pupae of the giant whitefly, Aleurodicus dugesii, produce large quantities of external lipids, both as waxy particles and as waxy filaments. The nymphs and pupae extrude filaments from two dorsal rows of five pores each. Filaments can attain lengths of 5-8 cm. The external lipids of nymphs and pupae consist largely of long-chain aldehydes, alcohols, acetate esters and wax esters. Hydrocarbons are minor components. Soon after hatching, the nymph produced an unidentified waxy fringe extruded laterally from its margin. After molting to the second instar, long, hollow, waxy filaments were produced by the immature stages. The major lipid class associated with the filaments was saturated wax esters (89%), mainly C44, C46 and C60. Associated with formation of the filaments were waxy particles in the shape of curls, which peeled off of the extruding filaments. Similar but more tubular-shaped curls were also produced by numerous lateral pores so that, eventually, the curls completely camouflaged the nymph. The major lipid class of the curls was wax esters (50%), mainly C44 and C46. The cuticular surface lipids of the nymphs were mainly long-chain aldehydes (43%) and wax esters (27%). Unsaturated fatty acid moieties constituted 2 and 19% of the wax esters of curls and nymph cuticular surface lipids, respectively. The major lipid classes of pupae and of their palisade were long-chain aldehydes and alcohols. No unsaturated wax esters were detected in the filaments, but 30% of pupal and 21% of palisade surface wax esters were unsaturated in their fatty acid moieties, 16:1, 18:1 and 20:1.

Animals↗
PubMed1997

Effect of penetration enhancers and iontophoresis on the ultrastructure and cholecystokinin-8 permeability through porcine skin.

The present study explores the effect of chemical penetration enhancers and iontophoresis on the in vitro permeability of cholecystokinin-8 (CCK-8) through porcine epidermis and on the ultrastructural changes in stratum corneum as observed by transmission electron microscopy (TEM). Enhancer [i.e., ethanol (EtOH), and 10% oleic acid in combination with ethanol (OA/EtOH)] pretreatment significantly increased (p < 0.01) the permeability coefficient of CCK-8 in comparison with the control (pretreated epidermis without enhancer). Iontophoresis further increased the permeability of CCK-8 (p < 0.01) through the enhancer-pretreated epidermis in comparison with the control. These results showed the synergistic effect of iontophoresis and enhancers such as OA/EtOH that provides an additional driving force to maintain and control the target flux of CCK-8. The ultrastructure of stratum corneum treated with ethanol demonstrated a loss of structural components in the superficial stratum corneum cell layers. OA/EtOH transformed the highly compact cells of stratum corneum into a looser network of filaments, creating an increased free volume and greater intracellular surface area. Treatment of stratum corneum with OA/EtOH followed by iontophoresis resulted in further swelling of stratum corneum cell layers. In conclusion, OA/EtOH in combination with iontophoresis increased the permeability of CCK-8 by loosening and swelling of stratum corneum cell layers.

Animals↗
PubMed1985

Chloramphenicol stimulation of light harvesting chlorophyll protein complex accumulation in a chlorophyll B deficient wheat mutant.

As compared with normal wheat leaves, the chlorina wheat mutant, designated CD3, has a high chlorophyll a/b ratio and a deficiency in the light harvesting chlorophyll protein (LHCP) complex. Applications of 200 micrograms per milliliter of d-threo-chloramphenicol to etiolated seedlings decreased the chlorophyll a/b ratio and increased the accumulation of the 27 kilodalton LHCP polypeptide and the LHCP complex in thylakoids of the mutant during greening. These data led to the suggestion that a protein encoded in chloroplast genes impaired either transcriptional, translational, or posttranslational events in CD3 wheat limiting the accumulation of the LHCP complex. The LHCP complex which accumulated in chloramphenicol treated wheat appeared functional even though chlorophyll protein complex accumulations were altered greatly in the wheat thylakoids. LHCP polypeptides were phosphorylated by action of a membrane protein kinase but yet photosystem II electron transport was impaired. The chloramphenicol treatment increased the photosystem I/photosystem II ratio of electron transport and the fluorescence emission ratio at 740 to 686 nanometers relative to those of untreated wheat. Chloramphenicol prevented development of normal granal thylakoids in normal wheat chloroplasts but not in those of the CD3 mutant. Elongated stacked thylakoids were observed in normal wheat. Net-like membranes and vesicles were noted in the stroma of chloroplasts from treated mutant seedlings.

Journal Article↗
PubMed1984

Regulation of excitation energy in a wheat mutant deficient in light-harvesting pigment protein complex.

Chloroplasts of the CD3 wheat mutant were deficient primarily in chlorophyll of light harvesting pigment proteins (LHPP) 1 and 2 and CP1a. The reduced level of protein associated with chlorophyll of LHPP1 and LHPP2 and the reduced level of low molecular weight polypeptides between 23 and 29 kilodaltons confirmed that the CD3 mutant was deficient in the LHPP complex. The high fluorescence emission ratio at 740 (F740) to 686 nanometers (F686) observed from chloroplasts of normal wheat following light induced phosphorylation of the LHPP complex was not noted from mutant chloroplasts. The long wavelength peak fluorescence emission (F740) was shifted to a shorter wavelength peak (F725) and was reduced in intensity compared to that of normal wheat thylakoids. The ratio of variable fluorescence to maximum fluorescence, a measure of PSII photochemical efficiency, was the same for the normal wheat and mutant leaves. The ratios of uncoupled photosystem I/photosystem II electron transport rates for mutant and normal wheat chloroplasts were similar at saturating light suggesting that absorbed excitation energy was distributed to the two photosystem reaction centers of the mutant in a similar manner as in the normal wheat. Proteins of the LHPP complex were differentially phosphorylated by action of a membrane protein kinase when both normal wheat and CD3 mutant thylakoids were irradiated without an electron transport chain acceptor. Even though the F740/F686 ratio was low in mutant thylakoids, the phosphorylation of the 27-kilodalton LHPP polypeptide was consistent with the mutant being in a state II condition. The data gave rise to the suggestion that the F740/F686 ratio might not indicate excitation energy distribution to the two photosystems in the mutant.

Journal Article↗
PubMed1984

Bacterial Symbionts in the Sugar Beet Root Maggot, Tetanops myopaeformis (von Röder).

Aerobic heterotrophic and facultative anaerobic bacteria were isolated from all developmental stages of the sugar beet root maggot, Tetanops myopaeformis (von Röder). Two distinct bacterial symbiotic relationships were observed. Serratia liquefaciens and Serratia marcescens were found to be associated with all developmental stages. Bacterial symbiont transmission occurred from one generation to the next. Symbionts were transferred from the male reproductive system to the female reproductive system, where both an internal infiltration of the egg chorion and an external smearing of the eggs occurred during oviposition. Pseudomonas maltophilia was found in association with the larval gut and the inner surface of the puparium. Electron microscopy of the inner puparial surface revealed symbionts within the chitinous wall. In vitro symbiont chitinase production was found, using both nephelometric (turbidimetric) and N-acetylglucosamine assays. A relationship appeared to exist between adult fly emergence and enzymatic chitin degradation of the puparium by the bacterial symbionts.

Journal Article↗
PubMed1980

Light and the correlation of chloroplast development and coupling of phosphorylation to electron transport.

Coupling of phosphorylation to electron transport was examined by measuring the photosynthetic control ratio for broken wheat plastids isolated from seedlings at different greening stages. The photosynthetic control ratio progressively increased during greening and tight coupling was noted after granal stacking and thylakoid elongation. ADP impaired nonphosphorylating (state 2) electron transport rates of plastids at extremely early stages of greening and interfered with photosynthetic control measurements. Partially developed plastids exhibited low nonphosphorylating electron flow rates but did not exhibit high phosphorylating or uncoupled electron transport rates to the same extent as nearly developed plastids. Prolamellar body dispersal, primary thylakoid production, and the development of photosynthetic control were stimulated equally by 48 minutes of low irradiance, in cycles of 2 minutes every 2 hours, or by 9 hours of continuous light of moderate irradiance. Wheat plastids that greened for 6 hours in continuous light of moderate intensity did not exhibit photosynthetic control or much differentiation beyond the etioplast stage. It is concluded that plastid differentiation and the development of photosynthetic control early in greening under continuous light were limited by developmental time (dark time) rather than by either light intensity or duration.

Journal Article↗
PubMed1979

A new method of preparing insects for scanning electron microscopy.

Acidified 2,2-dimethoxypropane (DMP), used as an alternative to regular fixation and dehydration methods for insects, was found to be the only successful means of preparing the sugarbeet root maggot larva, Tetanops myopaeformis (Röder) (Diptera:Otitidae), for the scanning electron microscope. No morphological changes were evident when DMP treated sugarbeet root maggot adults were compared to fresh (unfixed) adults and glutaraldehyde-osmium tetroxide fixed adults. The method has been used with success on several gropus of insects. Acidified CMP is quickly hydrolyzed by water in tissue to acetone and methanol. DMP is advantageous in that it penetrates water impermeable cuticles rapidly and saves several steps and time in the fixation and dehydration process.

Animals↗
PubMed1975

Partial Restoration of the High Rate of Plastid Pigment Development and the Ultrastructure of Plastids in Detached Water-stressed Wheat Leaves.

Detached etiolated wheat (Triticum aestivum L. cv. Chris) leaves accumulated plastid pigments at a high rate, developed chloroplasts with stacked thylakoids, and stored plastid starch when wetted on filter paper in light. A moderate water deficit of - 10 bars markedly reduced the accumulation of chlorophyll and carotenoids in the 8-day-old detached leaves during greening. delta-Aminolevulinic acid treatment of stressed leaf segments resulted in slightly increased pigment accumulations but benzyladenine application restored plastid pigment formation in stressed tissue to within 15% of the pigment content of the nonstressed detached leaves. The addition of delta-aminolevulinic acid to benzyladenine-treated stressed leaf segments improved both chlorophyll and carotenoid formation to nearly the amounts found in nonstressed leaf tissue. Stressed leaf sections developed plastids that were small, lacked starch, contained few thylakoids per granum, and possessed dilated thylakoids. Benzyladenine application to the stressed leaf segments did not restore normal plastid stacking but benzyladenine induced the formation of extended intergranal lamellae and stimulated pigment accumulations in both stressed and nonstressed detached leaves. Starch was absent in plastids of benzyladeninetreated leaf sections.

Journal Article↗
PubMed1970

Patient education.

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Health Education, Dental↗