High incidence of pollen theft in natural populations of a buzz-pollinated plant

To date, most research conducted on plant viruses has centred on agricultural systems where viruses greatly reduce economic output. Introduced viruses are globally common and there is a lack of knowledge around how they might affect natural populations. Although it has been suggested that infectious disease may have played an underestimated role in past species extinctions, there is little empirical evidence. Cook’s scurvy grass (Lepidium oleraceum Sparrm. ex G.Forst; Brassicaceae) is a threatened coastal plant endemic to New Zealand. Following the discovery of Turnip mosaic virus (TuMV) in some glasshouse cultivated specimens, we surveyed wild extant Lepidium populations on the Otago coast for TuMV while screening for two other common crop viruses. We show that TuMV is almost ubiquitous among remaining wild L. oleraceum populations on the South Island’s east coast and report the first record of L. oleraceum as a host for both Cauliflower mosaic virus and Turnip yellows virus. The high incidence of virus infection throughout the study populations may make this system one of the first examples of introduced viruses affecting the conservation of a threatened plant species.

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Fate of Escherichia coli O157:H7 on Fresh-Cut Apple Tissue and Its Potential for Transmission by Fruit Flies

Applied and Environmental Microbiology ◽

10.1128/aem.65.1.1-5.1999 ◽

1999 ◽

Vol 65 (1) ◽

pp. 1-5 ◽

Cited By ~ 132

Author(s):

W. J. Janisiewicz ◽

W. S. Conway ◽

M. W. Brown ◽

G. M. Sapers ◽

P. Fratamico ◽

...

Keyword(s):

Escherichia Coli ◽

Natural Populations ◽

Apple Fruit ◽

Fruit Flies ◽

Escherichia Coli O157 ◽

Initial Inoculum ◽

E Coli ◽

Time Period ◽

High Incidence ◽

Apple Tissue

ABSTRACT Pathogenic Escherichia coli O157:H7, as well as nonpathogenic strains ATCC 11775 and ATCC 23716, grew exponentially in wounds on Golden Delicious apple fruit. The exponential growth occurred over a longer time period on fruit inoculated with a lower concentration of the bacterium than on fruit inoculated with a higher concentration. The bacterium reached the maximum population supported in the wounds regardless of the initial inoculum concentrations. Populations of E. coli O157:H7 in various concentrations of sterilized apple juice and unsterilized cider declined over time and declined more quickly in diluted juice and cider. The decline was greater in the unsterilized cider than in juice, which may have resulted from the interaction of E. coli O157:H7 with natural populations of yeasts that increased with time. Experiments on the transmission of E. coli by fruit flies, collected from a compost pile of decaying apples and peaches, were conducted with strain F-11775, a fluorescent transformant of nonpathogenic E. coli ATCC 11775. Fruit flies were easily contaminated externally and internally with E. coli F-11775 after contact with the bacterium source. The flies transmitted this bacterium to uncontaminated apple wounds, resulting in a high incidence of contaminated wounds. Populations of the bacterium in apple wounds increased significantly during the first 48 h after transmission. Further studies under commercial conditions are necessary to confirm these findings.

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A High Incidence of Prophage Carriage among Natural Isolates of Streptococcus pneumoniae

Journal of Bacteriology ◽

10.1128/jb.181.12.3618-3625.1999 ◽

1999 ◽

Vol 181 (12) ◽

pp. 3618-3625 ◽

Cited By ~ 48

Author(s):

Mario Ramirez ◽

Elena Severina ◽

Alexander Tomasz

Keyword(s):

Streptococcus Pneumoniae ◽

Natural Populations ◽

Molecular Size ◽

Clinical Isolates ◽

Genetic Determinant ◽

Extrachromosomal Dna ◽

Widespread Occurrence ◽

High Incidence ◽

Multiple Copies ◽

Natural Isolates

ABSTRACT The majority (591 of 791, or 76%) of Streptococcus pneumoniae clinical isolates examined showed the presence of two or more chromosomal SmaI fragments that hybridized with thelytA-specific DNA probe. Only one of these fragments, frequently having an approximate molecular size of 90 kb, was shown to carry the genetic determinant of the pneumococcal autolysin (N-acetylmuramic acid-l-alanine amidase). Strains carrying multiple copies of lytA homologues included both antibiotic-susceptible and -resistant isolates as well as a number of different serotypes and strains recovered from geographic sites on three continents. Mitomycin C treatment of strains carrying several lytA-hybridizing fragments caused the appearance of extrachromosomal DNA hybridizing to the lytA gene, followed by lysis of the bacteria. Such lysates contained phage particles detectable by electron microscopy. The findings suggest that thelytA-hybridizing fragments in excess of the hostlytA represent components of pneumococcal bacteriophages. The high proportion of clinical isolates carrying multiple copies oflytA indicates the widespread occurrence of lysogeny, which may contribute to genetic variation in natural populations of pneumococci.

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High-voltage electron microscopy of maxillary gland of spirochete-infected brine shrimp: lesion of efferent tubule

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100103875 ◽

1988 ◽

Vol 46 ◽

pp. 362-363

Author(s):

G. E. Tyson ◽

M. J. Song

Keyword(s):

Electron Microscopy ◽

High Voltage ◽

Brine Shrimp ◽

Natural Populations ◽

Three Dimensional ◽

Dimensional Structure ◽

High Voltage Electron Microscopy ◽

Voltage Electron ◽

High Voltage Electron ◽

Infected Adult

Natural populations of the brine shrimp, Artemia, may possess spirochete- infected animals in low numbers. The ultrastructure of Artemia's spirochete has been described by conventional transmission electron microscopy. In infected shrimp, spirochetal cells were abundant in the blood and also occurred intra- and extracellularly in the three organs examined, i.e. the maxillary gland (segmental excretory organ), the integument, and certain muscles The efferent-tubule region of the maxillary gland possessed a distinctive lesion comprised of a group of spirochetes, together with numerous small vesicles, situated in a cave-like indentation of the base of the tubule epithelium. in some instances the basal lamina at a lesion site was clearly discontinuous. High-voltage electron microscopy has now been used to study lesions of the efferent tubule, with the aim of understanding better their three-dimensional structure.Tissue from one maxillary gland of an infected, adult, female brine shrimp was used for HVEM study.

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Effect of acid deposition on trichome morphology and dogwood anthracnose biology

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100124604 ◽

1992 ◽

Vol 50 (1) ◽

pp. 840-841

Author(s):

Kyle T. Thornham ◽

R. Jay Stipes ◽

Randolph L. Grayson

Keyword(s):

Acid Deposition ◽

Disease Incidence ◽

Natural Populations ◽

Tree Disease ◽

Flowering Dogwood ◽

Discula Destructiva ◽

Disease Induction ◽

Dogwood Anthracnose ◽

Trichome Morphology ◽

Precipitation Events

Dogwood anthracnose, caused by Discula destructiva (1), is another new catastrophic tree disease that has ravaged natural populations of the flowering dogwood (Cornus florida) in the Appalachians over the past 15 years, and the epidemic is prognosticated to continue (2). An estimated 9.5 million acres have been affected, primarily in the Appalachian Mountains, from VA southwards, alone, and an estimated 50% of all dogwoods in PA have been killed. Since acid deposition has been linked experimentally with disease induction, and since the disease incidence and severity are more pronounced at higher elevations where lower pH precipitation events occur, we investigated the effect of acidic foliar sprays on moiphologic changes in the foliar cuticle and trichomes (3), the initial sites of infection and foci of Discula sporulation.

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The observation of defects on (100) CdTe surfaces by chemical etching

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100131759 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1424-1425

Author(s):

M.E. Lee

Keyword(s):

Single Crystal ◽

Grain Boundaries ◽

Single Crystals ◽

Chemical Etching ◽

Crystalline Perfection ◽

Crystalline Defects ◽

High Incidence ◽

Crystallographic Defects ◽

Cdznte Substrates ◽

Device Technology

The crystalline perfection of bulk CdTe substrates plays an important role in their use in infrared device technology. The application of chemical etchants to determine crystal polarity or the density and distribution of crystallographic defects in (100) CdTe is not well understood. The lack of data on (100) CdTe surfaces is a result of the apparent difficulty in growing (100) CdTe single crystal substrates which is caused by a high incidence of twinning. Many etchants have been reported to predict polarity on one or both (111) CdTe planes but are considered to be unsuitable as defect etchants. An etchant reported recently has been considered to be a true defect etchant for CdTe, MCT and CdZnTe substrates. This etchant has been reported to reveal crystalline defects such as dislocations, grain boundaries and inclusions in (110) and (111) CdTe. In this study the effect of this new etchant on (100) CdTe surfaces is investigated.The single crystals used in this study were (100) CdTe as-cut slices (1mm thickness) from Bridgman-grown ingots.

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